View source for MD20004 Modbus RTU 8 OUT / 12 IN (EN)

==== Description ====

<b>Universal 8-output and 12-input card controlled via RS485 and Modbus RTU</b><br>

The Modig Modbus 8 OUT / 12 IN module is equipped with 8 SPDT electromagnetic relays and 12 galvanically isolated inputs. All outputs and inputs are controlled and read using Modbus standard commands transmitted via the RS485 interface. The control interface features galvanic isolation and surge protection, ensuring stable operation even in installations exposed to severe interference. The communication and operation parameters of the module can be flexibly configured and adapted to the requirements of various applications.

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[[File:Modig_Modbus_8_12_1.png|none|900px|thumb|center]]

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<hr>

==== Key Features and Parameters ====

* 8 relay outputs – NC/NO contacts, 10 A, 250 V AC / 30 V DC

* 12 optoisolated inputs – ON/OFF type inputs, active upon applying a voltage in the range of 5…25 V

* Current consumption of optoisolated inputs – approx. 2…12 mA for voltages of 5…25 V

* RS485 interface with galvanic isolation and surge protection

* Configurable communication parameters:

** baud rate: 1200…1000000;

** parity: none/even/odd;

** stop bits: 1/1.5/2

* 5 V DC power supply (4.9…5.3 V DC) with a minimum current capacity of 1 A via a USB-C connector or a 2.1/5.5 DC barrel jack

* 7…28 V power supply, min. 1 A via a 3.81 mm Phoenix MC connector

* Control and configuration of settings via Modbus commands

* Measurement of the supply voltage value (on the 5V side) and module temperature

* Dimensions: 200x110x60 mm

* Mounting on a DIN-35 rail

<br>

<hr>

==== Relay Connectors ====

The relay contacts are routed to screw terminal blocks with a 5.08 mm pitch. Each of the 8 outputs offers normally closed (NC) and normally open (NO) contacts. When a given output is activated, the NO contact connects to the common contact (COM), while the NC contact disconnects from COM. The active state for a given output is indicated by an illuminated LED located next to the terminals of that connector. The layout of individual pinouts is shown in the figure.

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[[File:Modbus_8OUT_12IN_REL.png|none|600px|thumb|center]]

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An example circuit controlled by the Modig Modbus 8 OUT / 12 IN is shown in the figure.

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[[File:Modbus_8OUT_12IN_BULP.png|none|700px|thumb|center]]

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==== Input Connectors ====

The Modig Modbus 8 OUT / 12 IN module is equipped with 12 optoisolated inputs. A DC voltage ranging from 5…25 V with the correct polarity can be connected to the inputs, which will be read as an active state (logical 1). The current consumption in the active state is approx. 2…12 mA. The absence of voltage on the inputs will be read as an inactive state (logical 0).<br><br>

Each input has '+' and '-' contacts routed to screw terminal blocks with a 5.08 mm pitch. Connecting a voltage with the correct polarity will set the active state for that input and light up the LED located next to its terminals. The layout of the individual pinouts is shown in the figure.

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[[File:Modbus_8OUT_12IN_IN.png|none|600px|thumb|center]]

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<hr>

==== RS485 Interface ====

The RS485 interface is routed out as a 4-pin Phoenix Contact MC 3.81 mm connector. Depending on the installation, either only the A+ and B- lines or all T, A+, B-, G lines can be used. Their functions are described in the table.

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<center>

[[File:Modbus_8OUT_12IN_RS485.png|none|450px|thumb|center]]

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<center>

{| class="wikitable"  style="width: 1000px;"

|-

! style="text-align: center;"|Designation

! style="text-align: center;"|Function

|-

| style="text-align: center;"|<b>120 Ω / T</b>

| style="text-align: left;"|Activation of the internal 120 Ω terminating resistor. The resistor is active when the '''T''' terminal is connected to the '''A+''' terminal, e.g., using a jumper installed directly inside the plug.

|-

| style="text-align: center;"|<b>A+</b>

| style="text-align: left;"|Line '''A''' of the RS485 bus (positive potential)

|-

| style="text-align: center;"|<b>B-</b>

| style="text-align: left;"|Line '''B''' of the RS485 bus (negative potential)

|-

| style="text-align: center;"|<b>GND / G</b>

| style="text-align: left;"|Ground '''GND''' of the RS485 bus.

|}

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<br>

The RS485 interface is galvanically isolated from the other components and equipped with surge protection elements, ensuring stable operation even in installations exposed to severe interference.

<br><br>

The RS485 communication parameters are configured via Modbus commands; the default settings are: 19200, 8, none, 1.

<br><br>

The Modig Modbus 8 OUT / 12 IN module can be connected to an RS485 bus that connects up to 64 devices (including the module). Each device should be connected in such a way that no bus branching occurs – any stub connections should be kept as short as possible. It is recommended to connect 120 Ω terminating resistors at both ends of the bus. Modig Modbus has such a resistor integrated, but to activate it, the A+ and T terminals must be connected together inside the plug.

<br><br>

The figure shows a simplified diagram of the RS485 bus, terminated on one side with a 120 Ω terminating resistor and on the other side with the terminating resistor integrated into the module. Furthermore, correct and incorrect device connections to the bus are demonstrated.

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[[File:Modbus_8OUT_12IN_RS485_2.png|none|900px|thumb|center]]

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==== Power Supply ====

The Modig Modbus 8 OUT / 12 IN module is equipped with 3 different power connectors. Only one of them must be chosen to connect a power supply with the appropriate parameters and correct polarity. Detailed information can be found in the table and figure below.

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<center>

{| class="wikitable"  style="width: 1000px;"

|-

! style="text-align: center;"|Connector

! style="text-align: center;"|Function

|-

| style="text-align: center;"|<b>USB-C (J3)</b>

| style="text-align: left;"|Standard USB-C socket, serves solely as a power supply connector. A power adapter/charger with a voltage of 5 V DC (4.9…5.3 V) and a minimum current of 1 A must be connected.

|-

| style="text-align: center;"|<b>2.1/5.5 (J2)</b>

| style="text-align: left;"|A 2.1/5.5 mm barrel jack compatible with "wall wart" type power supplies. A power adapter/charger with a voltage of 5 V DC (4.9…5.3 V) and a minimum current of 1 A must be connected.

Pay attention to the polarity – center positive.

|-

| style="text-align: center;"|<b>MC 3.81 mm (J1)</b>

| style="text-align: left;"|A connector with a plug for wire termination. A voltage source in the range of 7…28 V DC and a minimum current of 0.5 A must be connected.

Pay attention to the polarity – positive terminal on the side facing the inputs.

|}

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[[File:Modbus_8OUT_12IN_PWR.png|none|500px|thumb|center]]

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<hr>
==== Indicator LEDs ====

There are two indicator LEDs on the Modig Modbus 8 OUT / 12 IN board that provide information about the device's operational status.

<br><br>

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{| class="wikitable"  style="width: 1000px;"

|-

! style="text-align: center;"|Indicator

! style="text-align: center;"|Function

|-

| style="text-align: center;"|<b>STA</b>

| style="text-align: left;"|An illuminated LED with short, cyclic blanking indicates proper operation of the device.

|-

| style="text-align: center;"|<b>BUS</b>

| style="text-align: left;"|A flashing LED indicates data is being received from the RS485 bus and Modbus commands are being processed.

|}

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<center>

[[File:Modbus_8OUT_12IN_LED.png|none|450px|thumb|center]]

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<hr>

==== Restoring Default Settings ====

There is a SET micro-button located on the module board. Pressing and holding it for approximately 5 seconds will restore all settings (configuration register values) to their defaults. This function is useful in situations where incorrect parameter configuration prevents sending Modbus commands to the module. Restoring default settings will reset the RS485 communication parameters to: 19200, 8, none, 1, and the module address to "1".

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[[File:Modbus_8OUT_12IN_SET.png|none|500px|thumb|center]]

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<hr>

==== Configuration Registers (Holding Registers) ====

All device parameters are defined by the values of configuration registers, known as Holding Registers. These registers can be read and written via Modbus commands, allowing the operation of the device to be modified. The list of registers and their functions are described in the table below.

<br><br>

<center>

{| class="wikitable"  style="width: 1000px;"

|-

! style="text-align: center;"|'''Register Number (hex)'''

! style="text-align: center;"|'''Name'''

! style="text-align: center;"|'''Description'''

! style="text-align: center;"|'''Default Value /'''

'''Value Range'''

|-

| style="text-align: center;"|x4000

| style="text-align: center;"|Address

| style="text-align: left;"|Specifies the module address for control via Modbus commands.

| style="text-align: center;"|1 (x0001)

1…255

|-

| style="text-align: center;"|x4002

| style="text-align: center;"|Coils

| style="text-align: left;"|Contains a value specifying the number of outputs (Coils) available in the module.<br> Read-only value.

| style="text-align: center;"|16 (x0010)

|-

| style="text-align: center;"|x4004

| style="text-align: center;"|Inputs

| style="text-align: left;"|Contains a value specifying the number of inputs (Discrete inputs) available in the module.<br>

Read-only value.

| style="text-align: center;"|0 (x0000)

|-

| style="text-align: center;"|x4006

| style="text-align: center;"|Baud

| style="text-align: left;"|Specifies the RS485 communication speed (baud rate). <br>Value without the last 2 zeros, e.g.:<br>

1200 = 12 = x000C; 2400 = 24 = x0018<br>

4800 = 48 = x0030; 9600 = 96 = x0060<br>

19200 = 192 = x00C0; 57600 = 576 = x0240<br>

115200 = 1152 = x0480;<br>

256000 = 2560 = x0A00<br>

| style="text-align: center;"|192 (x00C0)

12…10000

|-

| style="text-align: center;"|x4008

| style="text-align: center;"|Parity

| style="text-align: left;"|Specifies the parity for RS485 communication.<br> 0 - none; 1 - even; 2 - odd

| style="text-align: center;"|0 (x0000)

0…2

|-

| style="text-align: center;"|x400A

| style="text-align: center;"|Stop

| style="text-align: left;"|Specifies the stop bits for RS485 communication. <br>

1 - 1 stop bit; 2 - two stop bits

| style="text-align: center;"|1 (x0001)

1…2

|-

| style="text-align: center;"|x400C

| style="text-align: center;"|Broadcast

| style="text-align: left;"|Defines whether the device executes broadcast commands with an address value of 0 (x00). 0 - no, 1 - yes.

| style="text-align: center;"|1 (x0001)

0…1

|-

| style="text-align: center;"|x400E

| style="text-align: center;"|CRC

| style="text-align: left;"|Defines whether the device verifies the checksum in Modbus commands. 0 - no, 1 - yes.

| style="text-align: center;"|0 (x0000)

0…1

|-

| style="text-align: center;"|x4010

| style="text-align: center;"|Response

| style="text-align: left;"|Allows sending responses to Modbus commands.

0 - does not send any responses,<br>

1 - sends responses to Modbus commands

| style="text-align: center;"|1 (x0001)

0…1

|-

| style="text-align: center;"|x4012

| style="text-align: center;"|IO Offset

| style="text-align: left;"|Specifies the base value from which inputs (Discrete inputs) and outputs (Coils) are indexed.

0 - inputs/outputs start from 0 (0…15)<br>

1 - inputs/outputs start from 1 (1…16)

| style="text-align: center;"|1 (x0001)

0…1

|-

| style="text-align: center;"|x4014

and

x8000

| style="text-align: center;"|Version

| style="text-align: left;"|Contains the firmware version.

A value of 10 represents version 1.0, etc.<br>

Read-only value.

| style="text-align: center;"|10 (x00A0)

|-

| style="text-align: center;"|x2000

| style="text-align: center;"|ExBaud

| style="text-align: left;"|Allows setting communication parameters using one of the predefined values.

The lower byte corresponds to the baud rate:<br>

0 - 4800, 1 - 9600, 2 - 19200, 3 - 38400<br>

4 - 57600, 5 - 115200, 6 - 12800, 7 - 256000<br>

8 - alternative value<br>

The upper byte specifies the parity:<br>

0 - none, 1 - even, 2 - odd <br>

| style="text-align: center;"|x0002

x0000…x0208

|}

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<hr>

==== Measurement Input Registers (Input Registers) ====

The device is equipped with supply voltage and temperature measurement circuits, which allow monitoring the module's operating conditions and preventing failures. The measurement results are available in measurement input registers, known as Input Registers. These measurement registers can be read using Modbus commands.

<br><br>

<center>

{| class="wikitable"  style="width: 1000px;"

|-

! style="text-align: center;"|'''Register Number (hex)'''

! style="text-align: center;"|'''Name'''

! style="text-align: center;"|'''Description'''

! style="text-align: center;"|'''Value Range'''

|-

| style="text-align: center;"|x3000

| style="text-align: center;"|Voltage

| style="text-align: left;"|Measurement of the supply voltage value. A value of 495 = 4.95 V, etc. 

| style="text-align: center;"|330…550

|-

| style="text-align: center;"|x3002

| style="text-align: center;"|Temp

| style="text-align: left;"|Measurement of the module temperature. A temperature value of 24 (x0018) indicates 24 degrees C.<br>

The temperature range -20…-1 is stored as xFF14…xFF01.<br>

The temperature range 0…70 is stored as x0000…x0046.

| style="text-align: center;"|-20…-1 °C = 

xFF14…xFF01<br>

0…70 °C = <br>

x0000…0046

|}

</center>

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<hr>
==== Modbus Standard Control Commands ====

Each command in the Modbus standard has the form of a data frame, the structure of which is shown in the figure:

<center>

[[File:Modig_Modbus_16_modbus.png|none|450px|thumb|center]]

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Consecutive frames must be separated by an interval of at least 3.5 characters (the time required to transmit a full ASCII character), while the interval between the transmission of one character and the start of transmission of the next character within the same frame must not exceed 1.5 characters. These rules apply to communication speeds (baud rates) up to 19200.

<br><br>

If the communication speed is set above 19200, the minimum interval between frames has a constant value equal to 1.75 ms. Meanwhile, the interval between consecutive characters of the same frame must not exceed 0.75 ms.

<br><br>

Each device connected to the Modbus bus must be assigned a unique address. The address field is located in every transmitted frame, has a size of 1 byte, and can have a value in the range of 1…255. An address value of 0 is the so-called broadcast address and allows a command to be directed to all devices connected to the bus. In some systems, it is not recommended to set addresses above a value of 247.

<br><br>

By default, outputs and inputs are numbered starting from 1. In this case, the first output is output number 1 (x01), and the last is number 16 (0x10). The command descriptions and command examples refer specifically to this variant. However, the device can be configured so that outputs and inputs are numbered starting from 0. In that case, the first output is output number 0 (x00), and the last is number 15 (0x0F). If the output number to which the control/read command refers exceeds the number of outputs contained in the device (15 or 16, depending on the configuration), the command will not be executed and will remain without response.

<br><br>

There are several standard commands in the Modbus standard. Each of them, along with example commands and device responses, is described in the subsequent sections of this manual.

<br><br>

<hr>

==== List of Supported Modbus Commands ====

<center>

{| class="wikitable"  style="width: 1000px;"

|-

! style="width: 250px; text-align: center;"|'''Command Name'''

! style="text-align: center;"|'''Command Code'''

! style="text-align: center;"|'''Function'''

|-

| style="text-align: left;"|Write Single Coil

| style="text-align: center;"|'''x05'''

| style="text-align: left;"|Allows controlling the state of an output or outputs

|-

| style="text-align: left;"|Write Multiple Coils

| style="text-align: center;"|'''x0F'''

| style="text-align: left;"|Allows controlling the state of multiple outputs simultaneously, both turning specific outputs ON and OFF.

|-

| style="text-align: left;"|Read Coils

| style="text-align: center;"|'''x01'''

| style="text-align: left;"|Allows reading the state of an output or outputs

|-

| style="text-align: left;"|Read Discrete Inputs

| style="text-align: center;"|'''x02'''

| style="text-align: left;"|Allows reading the state of inputs. Since the Modig Modbus 16R device does not have inputs for reading states, it reads the state of the outputs in response to this command, similarly to the “Read Coils” command - x01.

|-

| style="text-align: left;"|Read Input Registers

| style="text-align: center;"|'''x04'''

| style="text-align: left;"|Allows reading values from the measurement input registers

|-

| style="text-align: left;"|Read Holding Registers

| style="text-align: center;"|'''x03'''

| style="text-align: left;"|Allows reading values from the configuration registers

|-

| style="text-align: left;"|Write Single Holding Register

| style="text-align: center;"|'''x06'''

| style="text-align: left;"|Allows setting a value in a configuration register

|-

| style="text-align: left;"|Write Multiple Holding Registers

| style="text-align: center;"|'''x10'''

| style="text-align: left;"|Allows setting values in several configuration registers

|}

</center>

<br>

<hr>

===== “Write Single Coil” Command - x05 =====

<br>

The x05 command allows controlling the state of an output or outputs.

<br>

<center>

{| class="wikitable"  style="width: 1000px;"

|-

! style="text-align: center;" scope="row" colspan="2"|'''Data frame with x05 command'''

! style="text-align: left;"|'''01 05 00 00 FF 00 8C 3A'''

|-

! style="text-align: center;"|'''Byte Number'''

! style="text-align: center;"|'''Value (hex)'''

! style="text-align: left;"|'''Meaning'''

|-

| style="text-align: center;"|1

| style="text-align: center;"|x01

| style="text-align: left;"|Target device address

|-

| style="text-align: center;"|2

| style="text-align: center;"|x05

| style="text-align: left;"|“Write Single Coil” command - controlling a single output

|-

| style="text-align: center;"|3…4

| style="text-align: center;"|x0000

| style="text-align: left;"|Number of the output to be controlled:

0 - none of the outputs, 1 - output 1 (first), 8 - output 8 (last)

x00FF - controls all outputs - from 1 to 8

|-

| style="text-align: center;"|5…6

| style="text-align: center;"|xFF00

| style="text-align: left;"|Value specifying the task to be executed:

x0000 - turn off (OFF), xFF00 - turn on (ON),

x5500 - toggle the state to its opposite (TOGGLE) ON->OFF / OFF->ON

|-

| style="text-align: center;"|7…8

| style="text-align: center;"|x8C3A

| style="text-align: left;"|CRC16 checksum

|-

! style="text-align: center;" scope="row" colspan="2"|'''Response'''

! style="text-align: left;"|'''The device that reads and executes the command will send an identical frame in response: <br>01 05 00 00 FF 00 8C 3A'''

|}

</center>

<br>

Similar commands:

*A5 05 00 08 55 00 6A 7C - x05 command to the device with address 165 (xA5), output no. 8 (x0008) will toggle its state to the opposite (x5500)

:Response: A5 05 00 08 55 00 6A 7C

<br>

*14 05 00 01 00 00 9E CF - x05 command to the device with address 20 (x14), output no. 1 (x0001) will be turned OFF (x0000)

:Response: 14 05 00 01 00 00 9E CF

<br>

*29 05 00 FF FF 00 BA 22 - x05 command to the device with address 41 (x29), all outputs (x00FF) will be turned ON (xFF00)

:Response: 29 05 00 FF FF 00 BA 22

<br>

<hr>

===== “Write Multiple Coils” Command - x0F =====

<br>

The x0F command allows controlling the state of multiple outputs simultaneously, both turning specific outputs ON and OFF.

<br><br>

<center>

{| class="wikitable"  style="width: 1000px;"

|-

! style="text-align: center;" scope="row" colspan="2"|'''Data frame with x0F command'''

! style="text-align: left;"|'''01 0F 00 01 00 03 02 00 05 27 76'''

|-

! style="text-align: center;"|'''Byte Number'''

! style="text-align: center;"|'''Value (hex)'''

! style="text-align: left;"|'''Meaning'''

|-

| style="text-align: center;"|1

| style="text-align: center;"|x01

| style="text-align: left;"|Target device address

|-

| style="text-align: center;"|2

| style="text-align: center;"|x0F

| style="text-align: left;"|“Write Multiple Coils” command - controlling multiple outputs

|-

| style="text-align: center;"|3…4

| style="text-align: center;"|x0001

| style="text-align: left;"|Number of the output from which control will begin:

0 - none of the outputs will be controlled,

1 - from output 1 (first), 8 - from output 8 (last)

|-

| style="text-align: center;"|5…6

| style="text-align: center;"|x0003

| style="text-align: left;"|Number of outputs to be controlled:

0 - none of the outputs will be controlled

1 - one output, 8 - up to 8 outputs to be controlled

|-

| style="text-align: center;"|7

| style="text-align: center;"|x02

| style="text-align: left;"|Number of data bytes containing the control sequence - must be 2

|-

| style="text-align: center;"|8…9

| style="text-align: center;"|x0005

| style="text-align: left;"|Control sequence, LSB -> output No. 1.

Bits with a value of 0 turn the outputs OFF,

bits with a value of 1 turn the outputs ON.<br>

x0005 = 00000000 00000101 - outputs 1 and 3 are turned ON

|-

| style="text-align: center;"|10...11

| style="text-align: center;"|x27 76

| style="text-align: left;"|CRC16 checksum

|-

! style="text-align: center;" scope="row" colspan="2"|'''Response'''

! style="text-align: left;"|'''The device that reads and executes the command will send the following frame in response: '''

<br>'''01 0F 00 01 00 03 44 0A'''

|-

| style="text-align: center;"|1

| style="text-align: center;"|x01

| style="text-align: left;"|Address of the responding device

|-

| style="text-align: center;"|2

| style="text-align: center;"|x0F

| style="text-align: left;"|“Write Multiple Coils” command - controlling outputs

|-

| style="text-align: center;"|3...4

| style="text-align: center;"|x0001

| style="text-align: left;"|Number of the output from which control was initiated

|-

| style="text-align: center;"|5...6

| style="text-align: center;"|x0003

| style="text-align: left;"|Number of outputs that were actually controlled

|-

| style="text-align: center;"|7...8

| style="text-align: center;"|x440A

| style="text-align: left;"|CRC16 checksum

|}

</center>

<br>

If the number of outputs to be set exceeds the number of outputs available in the device (taking into account the starting output number), the command will be executed correctly for the existing outputs. The response will return the number of outputs that were actually controlled.

<br><br>

Similar commands:

*A5 0F 00 03 00 04 02 00 07 6C E6 - x0F command to the device with address 165 (xA5), controls 4 (x0004) outputs starting from output No. 3 (x0003), the control sequence is x0007 (00000000 00000111), which will turn ON outputs 3, 4, 5 and turn OFF output 6.

:Response: A5 0F 00 03 00 04 2C BD

*14 0F 00 06 00 05 02 00 00 14 DA - x0F command to the device with address 20 (x14), controls 5 (x0005) outputs starting from output No. 6 (x0006), the control sequence is x0000 (00000000 00000000), which will turn OFF outputs 6, 7, 8.

:Response: 14 0F 00 06 00 03 F7 0E (3 outputs controlled instead of 5)

*29 0F 00 01 00 10 02 FF FF 1C 40 - x0F command to the device with address 41 (x29), controls 16 (x0010) outputs starting from output No. 1 (x0001), the control sequence is xFFFF (11111111 11111111), which will turn ON all outputs from 1 to 8.

:Response: 29 0F 00 01 00 08 03 E5

<br>

<hr>

===== “Read Coils” Command - x01 ===== 

<br>

The x01 command allows reading the state of an output or outputs.

<br><br>

<center>

{| class="wikitable"  style="width: 1000px;"

|-

! style="text-align: center;" scope="row" colspan="2"|'''Data frame with x01 command'''

! style="text-align: left;"|'''01 01 00 02 00 04 9C 09'''

|-

! style="text-align: center;"|'''Byte Number'''

! style="text-align: center;"|'''Value (hex)'''

! style="text-align: left;"|'''Meaning'''

|-

| style="text-align: center;"|1

| style="text-align: center;"|x01

| style="text-align: left;"|Target device address

|-

| style="text-align: center;"|2

| style="text-align: center;"|x01

| style="text-align: left;"|“Read Coils” command - reading the state of outputs

|-

| style="text-align: center;"|3…4

| style="text-align: center;"|x0002

| style="text-align: left;"|Number of the output from which the status reading will begin:

2 - read starting from output No. 2

|-

| style="text-align: center;"|5…6

| style="text-align: center;"|x0004

| style="text-align: left;"|Value specifying how many outputs will be read:

4 - reading 4 outputs, i.e.: 2, 3, 4, and 5

|-

| style="text-align: center;"|7…8

| style="text-align: center;"|x9C09

| style="text-align: left;"|CRC16 checksum

|-

! style="text-align: center;" scope="row" colspan="2"|'''Response'''

! style="text-align: left;"|'''The device that reads and executes the command will send the following frame in response:<br>01 01 02 00 0C B9 F9'''

|-

| style="text-align: center;"|1

| style="text-align: center;"|x01

| style="text-align: left;"|Address of the responding device

|-

| style="text-align: center;"|2

| style="text-align: center;"|x01

| style="text-align: left;"|“Read Coils” command - reading the state of outputs

|-

| style="text-align: center;"|3

| style="text-align: center;"|x02

| style="text-align: left;"|Number of data bytes containing the response - 2

|-

| style="text-align: center;"|4…5

| style="text-align: center;"|x000C

| style="text-align: left;"|State of outputs: 2 - OFF (0), 3 - OFF (0), 4 - ON (1), 5 - ON (1)

Binary: 00000000 00001100

|-

| style="text-align: center;"|6…7

| style="text-align: center;"|xB9F9

| style="text-align: left;"|CRC16 checksum

|}

</center>

<br>

Similar commands:

*A5 01 00 06 00 02 44 EE - x01 command to the device with address 165 (xA5), reading the state of 2 (x0002) outputs, starting from output 6 (x0006).

:Response: A5 01 02 00 02 49 E4 - only output No. 7 is active (x0002)

<br>

*14 01 00 08 00 01 7E CD - x01 command to the device with address 20 (x14), reading the state of one (x0001) output, starting from output 8 (x0008).

:Response: 14 01 02 00 00 B4 3F - output turned OFF (x0000)

<br>

*29 01 00 20 00 08 3A 2E - x01 command to the device with address 41 (x29), reading the state of 8 (x0008) outputs, starting from output 32 (x0020).

:Response: no response - cannot read status starting from output 32

<br>

If the number of outputs to be read exceeds the number of outputs available in the device (taking into account the starting output number), non-existent outputs in the response will always have an OFF (0) state.

<br><br>

<hr>

===== “Read Discrete Inputs” Command - x02 ===== 

<br>

The x02 command allows reading the state of inputs. Inputs with voltage connected will have an active state - 1, unconnected inputs will have a state of 0.

<br><br>

<center>

{| class="wikitable"  style="width: 1000px;"

|-

! style="text-align: center;" scope="row" colspan="2"|'''Data frame with x02 command'''

! style="text-align: left;"|'''01 02 00 02 00 04 D8 09'''

|-

! style="text-align: center;"|'''Byte Number'''

! style="text-align: center;"|'''Value (hex)'''

! style="text-align: left;"|'''Meaning'''

|-

| style="text-align: center;"|1

| style="text-align: center;"|x01

| style="text-align: left;"|Target device address

|-

| style="text-align: center;"|2

| style="text-align: center;"|x02

| style="text-align: left;"|“Read Discrete Inputs” command - reading the state of inputs

|-

| style="text-align: center;"|3…4

| style="text-align: center;"|x0002

| style="text-align: left;"|Number of the input from which the status reading will begin:

2 - read starting from input No. 2

|-

| style="text-align: center;"|5…6

| style="text-align: center;"|x0004

| style="text-align: left;"|Value specifying how many inputs will be read:

4 - reading 4 inputs, i.e.: 2, 3, 4, and 5

|-

| style="text-align: center;"|7…8

| style="text-align: center;"|xD809

| style="text-align: left;"|CRC16 checksum

|-

! style="text-align: center;" scope="row" colspan="2"|'''Response'''

! style="text-align: left;"|'''The device that reads and executes the command will send the following frame in response:<br>01 02 02 00 0C B9 BD'''

|-

| style="text-align: center;"|1

| style="text-align: center;"|x01

| style="text-align: left;"|Address of the responding device

|-

| style="text-align: center;"|2

| style="text-align: center;"|x02

| style="text-align: left;"|“Read Discrete Inputs” command - reading the state of inputs

|-

| style="text-align: center;"|3

| style="text-align: center;"|x02

| style="text-align: left;"|Number of data bytes containing the response - 2

|-

| style="text-align: center;"|4…5

| style="text-align: center;"|x000C

| style="text-align: left;"|State of inputs: 2 - inactive (0), 3 - inactive (0), 4 - active (1), 5 - active (1); 

Binary: 00000000 00001100

|-

| style="text-align: center;"|6…7

| style="text-align: center;"|xB9BD

| style="text-align: left;"|CRC16 checksum

|}

</center>

<br>

Similar commands:

*A5 02 00 02 00 06 40 EC - x02 command to the device with address 165 (xA5), reading the state of 6 (x0006) inputs, starting from input 2 (x0002).

:Response: A5 02 02 00 02 49 A0 - only input No. 3 is active (x0002)

<br>

*14 02 00 08 00 01 3A CD - x02 command to the device with address 20 (x14), reading the state of one (x0001) input, starting from input 8 (x0008).

:Response: 14 02 02 00 00 B4 7B - input inactive (x0000)

<br>

*29 02 00 20 01 00 7E 78 - x02 command to the device with address 41 (x29), reading the state of 16 (x0010) inputs, starting from input 32 (x0020).

:Response: no response - cannot read status starting from input 32

<br>

If the number of inputs to be read exceeds the number of inputs available in the device (taking into account the starting input number), non-existent inputs in the response will always have an inactive (0) state.

<br>

<hr>

===== “Read Input Registers” Command - x04 ===== 

<br>

The x04 command allows reading values from the measurement input registers. In the Modig Modbus device, it is possible to measure the supply voltage on the 5 V input (it does not measure the voltage on the 7…28 V input) and the module temperature.

<br><br>

<center>

{| class="wikitable"  style="width: 1000px;"

|-

! style="text-align: center;" scope="row" colspan="2"|'''Data frame with x04 command'''

! style="text-align: left;"|'''01 04 30 00 00 02 7E CB'''

|-

! style="text-align: center;"|'''Byte Number'''

! style="text-align: center;"|'''Value (hex)'''

! style="text-align: left;"|'''Meaning'''

|-

| style="text-align: center;"|1

| style="text-align: center;"|x01

| style="text-align: left;"|Target device address

|-

| style="text-align: center;"|2

| style="text-align: center;"|x04

| style="text-align: left;"|“Read Input Registers” command - reading measurement input registers

|-

| style="text-align: center;"|3…4

| style="text-align: center;"|x3000

| style="text-align: left;"|Number of the register from which the reading will begin.

x3000 - reading the supply voltage measurement

x3002 - reading the module temperature measurement

|-

| style="text-align: center;"|5…6

| style="text-align: center;"|x0002

| style="text-align: left;"|Value specifying how many registers will be read:

1 - one, e.g., only voltage; 2 - both measurement registers

|-

| style="text-align: center;"|7…8

| style="text-align: center;"|x7ECB

| style="text-align: left;"|CRC16 checksum

|-

! style="text-align: center;" scope="row" colspan="2"|'''Response'''

! style="text-align: left;"|'''The device that reads and executes the command will send the following frame in response:<br>01 04 04 02 06 00 18 1A 37'''

|-

| style="text-align: center;"|1

| style="text-align: center;"|x01

| style="text-align: left;"|Address of the responding device

|-

| style="text-align: center;"|2

| style="text-align: center;"|x04

| style="text-align: left;"|“Read Input Registers” command - reading measurement input registers

|-

| style="text-align: center;"|3

| style="text-align: center;"|x04

| style="text-align: left;"|Number of data bytes containing the response - 4

|-

| style="text-align: center;"|4…5

| style="text-align: center;"|x0206

| style="text-align: left;"|Voltage value - x0206 = 518, which means 5.18 V

|-

| style="text-align: center;"|6…7

| style="text-align: center;"|x0018

| style="text-align: left;"|Temperature value - x0018 = 24, which means 24 degrees C

The temperature range -20…-1 is stored as xFF14…xFF01

The temperature range 0…70 is stored as x0000…x0046

|-

| style="text-align: center;"|8…9

| style="text-align: center;"|x1A37

| style="text-align: left;"|CRC16 checksum

|}

</center>

<br>

Similar commands:

*A5 04 30 00 00 01 27 EE - x04 command to the device with address 165 (xA5), reading one register (x0001) numbered x3000, which is the supply voltage measurement register.

:Response: A5 04 02 01 F0 49 A0 - voltage is 4.96 V (x01F0 = 496)

*14 04 30 08 00 02 FD CC - x04 command to the device with address 20 (x14), reading two (x0002) measurement registers starting from number x3008.

:Response: no response - there is no measurement register numbered x3008.

*29 04 30 02 00 02 7E 78 - x04 command to the device with address 41 (x29), reading two (x0002) measurement registers starting from number x3002.

:Response: A5 04 02 00 18 C8 E3 - the device has no measurement registers higher than x3002, therefore only one register numbered x3002 was read - module temperature = 24 (x0018) and there are only two data bytes (x02) in the response.

<br>

<hr>

===== “Read Holding Registers” Command - x03 ===== 

<br>

The x03 command allows reading values from the configuration registers.

<br><br>

<center>

{| class="wikitable"  style="width: 1000px;"

|-

! style="text-align: center;" scope="row" colspan="2"|'''Data frame with x03 command'''

! style="text-align: left;"|'''01 03 40 00 00 01 91 CA'''

|-

! style="text-align: center;"|'''Byte Number'''

! style="text-align: center;"|'''Value (hex)'''

! style="text-align: left;"|'''Meaning'''

|-

| style="text-align: center;"|1

| style="text-align: center;"|x01

| style="text-align: left;"|Target device address

|-

| style="text-align: center;"|2

| style="text-align: center;"|x03

| style="text-align: left;"|“Read Holding Registers” command - reading configuration registers

|-

| style="text-align: center;"|3…4

| style="text-align: center;"|x4000

| style="text-align: left;"|Number of the register from which the reading will begin.

Available registers are in the ranges x4000…x4014 as well as x2000, x8000

|-

| style="text-align: center;"|5…6

| style="text-align: center;"|x0001

| style="text-align: left;"|Value specifying how many registers will be read:

1 - one, etc., up to a maximum of 8

|-

| style="text-align: center;"|7…8

| style="text-align: center;"|x91CA

| style="text-align: left;"|CRC16 checksum

|-

! style="text-align: center;" scope="row" colspan="2"|'''Response'''

! style="text-align: left;"|'''The device that reads and executes the command will send the following frame in response:<br>01 03 02 00 01 79 84'''

|-

| style="text-align: center;"|1

| style="text-align: center;"|x01

| style="text-align: left;"|Address of the responding device

|-

| style="text-align: center;"|2

| style="text-align: center;"|x03

| style="text-align: left;"|“Read Holding Registers” command - reading configuration registers

|-

| style="text-align: center;"|3

| style="text-align: center;"|x02

| style="text-align: left;"|Number of data bytes containing the response - 2

|-

| style="text-align: center;"|4…5

| style="text-align: center;"|x0001

| style="text-align: left;"|Register numbered x4000 contains the address for Modbus commands, which in this case is 1 (x0001)

|-

| style="text-align: center;"|6…7

| style="text-align: center;"|x7984

| style="text-align: left;"|CRC16 checksum

|}

</center>

<br>

Similar commands:

*A5 03 40 06 00 04 28 EE - x03 command to the device with address 165 (xA5), reading four configuration registers (x0004), starting from number (x4006).

:Response: A5 03 08 00 C0 00 00 00 01 00 01 C5 DB - values of 4 configuration registers, i.e., 8 data bytes

<br>

*14 03 80 00 00 01 AF 0F - x03 command to the device with address 20 (x14), reading one (x0001) configuration register numbered x8000, which is the firmware version.

:Response: 14 03 02 00 A0 B5 FF - response of 2 bytes (x00A0) = 10, which means firmware version 1.0

<br>

<hr>

===== “Write Single Holding Register” Command - x06 ===== 

<br>

The x06 command allows setting a value in a configuration register.

<br><br>

<center>

{| class="wikitable"  style="width: 1000px;"

|-

! style="text-align: center;" scope="row" colspan="2"|'''Data frame with x06 command'''

! style="text-align: left;"|'''01 06 40 00 00 01 5D CA'''

|-

! style="text-align: center;"|'''Byte Number'''

! style="text-align: center;"|'''Value (hex)'''

! style="text-align: left;"|'''Meaning'''

|-

| style="text-align: center;"|1

| style="text-align: center;"|x01

| style="text-align: left;"|Target device address

|-

| style="text-align: center;"|2

| style="text-align: center;"|x06

| style="text-align: left;"|“Write Single Holding Register” command - writing a configuration register

|-

| style="text-align: center;"|3…4

| style="text-align: center;"|x4000

| style="text-align: left;"|Number of the register to which the new value will be written.

Available registers are in the ranges x4000, x4006…x4012, and x2000

|-

| style="text-align: center;"|5…6

| style="text-align: center;"|x0001

| style="text-align: left;"|Value to be written into the register

|-

| style="text-align: center;"|7…8

| style="text-align: center;"|x5DCA

| style="text-align: left;"|CRC16 checksum

|-

! style="text-align: center;" scope="row" colspan="2"|'''Response'''

! style="text-align: left;"|'''The device that reads and executes the command will send an identical frame in response:<br> 01 06 40 00 00 01 5D CA'''

|}

</center>

<br>

Similar commands:

*A5 06 40 00 00 04 84 ED - x06 command to the device with address 165 (xA5), writing configuration register numbered x4000 with a value of 4 (x0004), i.e., assigning a new address of 4.

:Response: A5 06 40 00 00 04 84 ED

<br>

*14 06 40 0C 00 00 5E CC - x06 command to the device with address 20 (x14), writing configuration register numbered x400C with a value of 0 (x0000), i.e., disabling broadcast command handling.

:Response: 14 06 40 0C 00 00 5E CC

<br>

<hr>

===== “Write Multiple Holding Registers” Command - x10 ===== 

<br>

The x10 command allows setting values in several configuration registers.

<br><br>

<center>

{| class="wikitable"  style="width: 1000px;"

|-

! style="text-align: center;" scope="row" colspan="2"|'''Data frame with x10 command'''

! style="text-align: left;"|'''01 10 40 0C 00 03 06 00 01 00 00 00 01 8F 7E'''

|-

! style="text-align: center;"|'''Byte Number'''

! style="text-align: center;"|'''Value (hex)'''

! style="text-align: left;"|'''Meaning'''

|-

| style="text-align: center;"|1

| style="text-align: center;"|x01

| style="text-align: left;"|Target device address

|-

| style="text-align: center;"|2

| style="text-align: center;"|x10

| style="text-align: left;"|“Write Multiple Holding Registers” command - writing several configuration registers

|-

| style="text-align: center;"|3…4

| style="text-align: center;"|x400C

| style="text-align: left;"|Number of the register from which writing will begin.

Available registers are in the ranges x4000, x4006…x4012, and x2000

|-

| style="text-align: center;"|5…6

| style="text-align: center;"|x0003

| style="text-align: left;"|Value specifying how many registers will be written:

1 - one, etc., up to a maximum of 8

|-

| style="text-align: center;"|7

| style="text-align: center;"|x06

| style="text-align: left;"|Number of data bytes containing the values to be written

|-

| style="text-align: center;"|8…13

| style="text-align: center;"|x0001<br>x0000<br>x0001

| style="text-align: left;"|Three values to be written into the configuration registers

|-

| style="text-align: center;"|14…17

| style="text-align: center;"|x8F7E

| style="text-align: left;"|CRC16 checksum

|-

! style="text-align: center;" scope="row" colspan="2"|'''Response'''

! style="text-align: left;"|'''The device that reads and executes the command will send the following frame in response:<br> 01 10 40 0C 00 03 55 CB'''

|-

| style="text-align: center;"|1

| style="text-align: center;"|x01

| style="text-align: left;"|Address of the responding device

|-

| style="text-align: center;"|2

| style="text-align: center;"|x10

| style="text-align: left;"|“Write Multiple Holding Registers” command - writing several configuration registers

|-

| style="text-align: center;"|3

| style="text-align: center;"|x400C

| style="text-align: left;"|Number of the register from which the value writing was initiated

|-

| style="text-align: center;"|4…5

| style="text-align: center;"|x0003

| style="text-align: left;"|Value specifying how many registers were successfully written

|-

| style="text-align: center;"|6…7

| style="text-align: center;"|x55CB

| style="text-align: left;"|CRC16 checksum

|}

</center>

<br>

Similar commands:

*A5 10 40 00 00 01 02 00 03 6D 52 - x10 command to the device with address 165 (xA5), writing one (x0001) configuration register starting from number x4000 with data of two bytes in length (x02) equal to x0003, i.e., assigning a new address of 3.

:Response: A5 10 40 00 00 03 8C EC

<br>

*14 10 40 0C 00 02 04 00 01 00 00 D6 F5 - x10 command to the device with address 20 (x14), writing two (x0002) configuration registers starting from number x400C with the values x0001 and x0000, i.e., enabling broadcast command handling and disabling CRC checksum verification.

:Response: 14 10 40 0C 00 02 96 CE

<br>

<hr>