Modbus TCP

You are currently viewing the documentation for the latest version (2.2.0). To access a different version, click the "Switch version" button located in the upper-right corner of the page.

■ If you are not sure which version of the product you are currently using, please feel free to contact Mech-Mind Technical Support.

Mech-MSR can communicate with external devices through Modbus TCP. Before you read the following content, make sure that the communication configuration has been completed in Mech-MSR.

About Modbus TCP

Mech-MSR supports communication with PLCs through the Modbus TCP protocol. In this communication mode, Mech-MSR acts as the server (slave) and the PLC acts as the client (master). All requests are initiated by the PLC, and Mech-MSR responds to them.

After the Modbus TCP communication service is enabled in Mech-MSR, the software starts listening on port 502 (default) for one or more Modbus clients.

Communication Workflow

The workflow of Modbus TCP communication is shown in the figure below.

See Input and Output Signals to learn the meaning of each signal.

Input and Output Signals

Mech-MSR supports the following standard Modbus function codes for accessing holding registers.

Function Code

Description

0x03

Read holding registers

0x06

Write a single holding register

0x10

Write multiple holding registers

Holding register addresses are logical addresses (displayed addresses), such as 40001 and 40005. The prefix 4 indicates that the register belongs to the 4x address space (holding registers), and the following digits indicate the register number.

During actual communication, the base address is 1, which means holding register addresses start from 40001. Therefore, the actual address = displayed address - 40001. For example, the actual address corresponding to 40001 is 0, and the actual address corresponding to 40005 is 4.

Input (from the PLC to Mech-MSR)	Output (from Mech-MSR to the PLC)
Module	Name	Bytes Occupied	Holding Register Address (4x)	Module	Name	Bytes Occupied	Holding Register Address (4x)
CONTROL_INPUT	Enable	1 byte	40001	CONTROL_OUTPUT	Heartbeat	1 byte	40065
Command trigger	Trigger acknowledge
Data read finished	Data ready
Reset output data	Command execution completed
Reserved	Reserved
Reserved	Reserved
Reserved	Reserved
Reserved	Error
Reserved	3 bytes	First 1 byte: 40001; last 2 bytes: 40002	Overall judgment result	1 byte	40065
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved	2 bytes	40066
COMMAND	Command code	2 bytes	40003	STATUS_CODE	Status code	2 bytes	40067
COMMAND_PARAM	Command parameter 1	2 bytes	40004	RESERVED	Reserved	2 bytes	40068
Command parameter 2	2 bytes	40005	JUDGE	Judgment result of ID 1 Judgment result of ID 2 Judgment result of ID 3 ...	8 bytes	40069~40072
Command parameter 3	2 bytes	40006
Command parameter 4	2 bytes	40007
Command parameter 5	2 bytes	40008
Command parameter 6	2 bytes	40009	VALUE	Measurement result of ID 1 Measurement result of ID 2 Measurement result of ID 3 ...	256 bytes (4 bytes x 64)	40073~40200
Command parameter 7	2 bytes	40010
Command parameter 8	2 bytes	40011
Command parameter 9	2 bytes	40012
Command parameter 10	2 bytes	40013
VAR_INPUT	Variable 1	4 bytes	40014~40015
Variable 2	4 bytes	40016~40017
Variable 3	4 bytes	40018~40019
Variable 4	4 bytes	40020~40021
Variable 5	4 bytes	40022~40023
Variable 6	4 bytes	40024~40025
Variable 7	4 bytes	40026~40027
Variable 8	4 bytes	40028~40029
Variable 9	4 bytes	40030~40031
Variable 10	4 bytes	40032~40033
RESERVED	Reserved	62 bytes	40034~40064

Input (from the PLC to Mech-MSR)

Output (from Mech-MSR to the PLC)

Module

Name

Bytes Occupied

Holding Register Address (4x)

Module

Name

Bytes Occupied

Holding Register Address (4x)

CONTROL_INPUT

Enable

1 byte

40001

CONTROL_OUTPUT

Heartbeat

1 byte

40065

Command trigger

Trigger acknowledge

Data read finished

Data ready

Reset output data

Command execution completed

Reserved

Error

Reserved

3 bytes

First 1 byte: 40001; last 2 bytes: 40002

Overall judgment result

1 byte

40065

Reserved

2 bytes

40066

COMMAND

Command code

2 bytes

40003

STATUS_CODE

Status code

2 bytes

40067

COMMAND_PARAM

Command parameter 1

2 bytes

40004

RESERVED

Reserved

2 bytes

40068

Command parameter 2

2 bytes

40005

JUDGE

Judgment result of ID 1

Judgment result of ID 2

Judgment result of ID 3

...

8 bytes

40069~40072

Command parameter 3

2 bytes

40006

Command parameter 4

2 bytes

40007

Command parameter 5

2 bytes

40008

Command parameter 6

2 bytes

40009

VALUE

Measurement result of ID 1

Measurement result of ID 2

Measurement result of ID 3

...

256 bytes

(4 bytes x 64)

40073~40200

Command parameter 7

2 bytes

40010

Command parameter 8

2 bytes

40011

Command parameter 9

2 bytes

40012

Command parameter 10

2 bytes

40013

VAR_INPUT

Variable 1

4 bytes

40014~40015

Variable 2

4 bytes

40016~40017

Variable 3

4 bytes

40018~40019

Variable 4

4 bytes

40020~40021

Variable 5

4 bytes

40022~40023

Variable 6

4 bytes

40024~40025

Variable 7

4 bytes

40026~40027

Variable 8

4 bytes

40028~40029

Variable 9

4 bytes

40030~40031

Variable 10

4 bytes

40032~40033

RESERVED

Reserved

62 bytes

40034~40064

Input (from the PLC to Mech-MSR)

CONTROL_INPUT

Address	Data	Description
0.0	Enable (Boolean)	Only when the enable signal is set to 1 are the other input signals considered valid.
0.1	Command trigger (Boolean)	Mech-MSR reads the command code and command parameters only when the command trigger signal changes from 0 to 1 (rising edge). After Mech-MSR returns the Trigger Acknowledge signal, the command trigger signal can be set to 0.
0.2	Data read finished (Boolean)	After the PLC finishes reading the data, set this signal to 1. Only after the PLC receives the Data Ready signal changing to 0 can this signal be set to 0.
0.3	Reset output data (Boolean)	When this signal is set to 1, the judgment results and measurement results received by the PLC (output) are cleared. At this point, the PLC can send a new command, and the related status code signals are also reset.
0.4	Reserved (Boolean)	Reserved field.
0.5	Reserved (Boolean)	Reserved field.
0.6	Reserved (Boolean)	Reserved field.
0.7	Reserved (Boolean)	Reserved field.
1.0~3.7	Reserved (Byte)	Reserved field.

Address

Data

Description

0.0

Enable (Boolean)

Only when the enable signal is set to 1 are the other input signals considered valid.

0.1

Command trigger (Boolean)

Mech-MSR reads the command code and command parameters only when the command trigger signal changes from 0 to 1 (rising edge). After Mech-MSR returns the Trigger Acknowledge signal, the command trigger signal can be set to 0.

0.2

Data read finished (Boolean)

After the PLC finishes reading the data, set this signal to 1. Only after the PLC receives the Data Ready signal changing to 0 can this signal be set to 0.

0.3

Reset output data (Boolean)

When this signal is set to 1, the judgment results and measurement results received by the PLC (output) are cleared. At this point, the PLC can send a new command, and the related status code signals are also reset.

0.4

Reserved (Boolean)

Reserved field.

0.5

Reserved (Boolean)

Reserved field.

0.6

Reserved (Boolean)

Reserved field.

0.7

Reserved (Boolean)

Reserved field.

1.0~3.7

Reserved (Byte)

Reserved field.

COMMAND & COMMAND_PARAM

The following table lists the supported commands in the current protocol and their corresponding command codes (COMMAND), command parameters (COMMAND_PARAM), and descriptions.

Command	COMMAND	COMMAND_PARAM	Description
execute	1	Project ID. Only 1 project ID can be set at a time.	Used to trigger a project to run and obtain the project’s judgment results and measurement results.
trigger	2	Project ID. 1 to 4 project IDs can be set at a time.	Used to trigger a project to run.
return	3	Project ID. Only 1 project ID can be set at a time.	Used to obtain the judgment results and measurement results of the specified project.
judge	4	Used to obtain the overall quality judgment result of the specified project or the quality judgment results of individual measurement items.
value	5	Mainly used to obtain the measurement values of the specified project.
recipe	6	Project ID and parameter recipe ID.	Used to switch the parameter recipe used by a project.
solution	7	Solution ID.	Used to switch a solution.
SetNumVar	8	Global variable ID. Only 1 can be set at a time.	Used to set the value of a numeric global variable. The variable value is passed through VAR_INPUT.
GetNumVar	9	Global variable ID. Only 1 can be set at a time.	Used to read the value of a numeric global variable. The result is returned through VALUE.

Command

COMMAND

COMMAND_PARAM

Description

execute

Project ID. Only 1 project ID can be set at a time.

Used to trigger a project to run and obtain the project’s judgment results and measurement results.

trigger

Project ID. 1 to 4 project IDs can be set at a time.

Used to trigger a project to run.

return

Project ID. Only 1 project ID can be set at a time.

Used to obtain the judgment results and measurement results of the specified project.

judge

Used to obtain the overall quality judgment result of the specified project or the quality judgment results of individual measurement items.

value

Mainly used to obtain the measurement values of the specified project.

recipe

Project ID and parameter recipe ID.

Used to switch the parameter recipe used by a project.

solution

Solution ID.

Used to switch a solution.

SetNumVar

Global variable ID. Only 1 can be set at a time.

Used to set the value of a numeric global variable. The variable value is passed through VAR_INPUT.

GetNumVar

Global variable ID. Only 1 can be set at a time.

Used to read the value of a numeric global variable. The result is returned through VALUE.

See Project List to learn how to view the project ID.
See Parameter Recipe to learn how to view the parameter recipe ID.
See Adjust Solution IDs to learn how to view and adjust the solution ID.
See Global Variable Manager to learn how to view and adjust the global variable ID.

VAR_INPUT

When the SetNumVar command is executed, the set value is written to VAR_INPUT.

Holding Register Address (4x)	Data	Description
40014~40015	Variable 1 (Float)	Numeric input parameter 1.
40016~40017	Variable 2 (Float)	Numeric input parameter 2.
40018~40019	Variable 3 (Float)	Numeric input parameter 3.
40020~40021	Variable 4 (Float)	Numeric input parameter 4.
40022~40023	Variable 5 (Float)	Numeric input parameter 5.
40024~40025	Variable 6 (Float)	Numeric input parameter 6.
40026~40027	Variable 7 (Float)	Numeric input parameter 7.
40028~40029	Variable 8 (Float)	Numeric input parameter 8.
40030~40031	Variable 9 (Float)	Numeric input parameter 9.
40032~40033	Variable 10 (Float)	Numeric input parameter 10.

Holding Register Address (4x)

Data

Description

40014~40015

Variable 1 (Float)

Numeric input parameter 1.

40016~40017

Variable 2 (Float)

Numeric input parameter 2.

40018~40019

Variable 3 (Float)

Numeric input parameter 3.

40020~40021

Variable 4 (Float)

Numeric input parameter 4.

40022~40023

Variable 5 (Float)

Numeric input parameter 5.

40024~40025

Variable 6 (Float)

Numeric input parameter 6.

40026~40027

Variable 7 (Float)

Numeric input parameter 7.

40028~40029

Variable 8 (Float)

Numeric input parameter 8.

40030~40031

Variable 9 (Float)

Numeric input parameter 9.

40032~40033

Variable 10 (Float)

Numeric input parameter 10.

Output (from Mech-MSR to the PLC)

CONTROL_OUTPUT

Address	Data	Description
0.0	Heartbeat signal (Boolean)	System heartbeat. It toggles every second. It can be used to determine whether the communication connection between the PLC and Mech-MSR is normal or disconnected.
0.1	Trigger acknowledge (Boolean)	When Mech-MSR receives the rising edge of the Command Trigger signal, this signal is set to 1. When the command trigger signal falls, this signal is set to 0.
0.2	Data ready (Boolean)	Mech-MSR writes data to the output port and waits for the PLC to read it. When the Data Read Finished signal is 1, this signal is set to 0.
0.3	Command execution completed (Boolean)	When command execution ends, this signal is set to 1, indicating that the command has been processed.
0.4	Reserved (Boolean)	Reserved field.
0.5	Reserved (Boolean)	Reserved field.
0.6	Reserved (Boolean)	Reserved field.
0.7	Error (Boolean)	When the status code returned by Mech-MSR is not 1, this signal is set to 1 to indicate an error.
1.0	Overall judgment result (Boolean)	The overall judgment result of the project. 1 indicates pass (OK), and 0 indicates fail (NG).
1.1~1.7	Reserved (Boolean)	Reserved field.
2.0~3.7	Reserved (Byte)	Reserved field.

Address

Data

Description

0.0

Heartbeat signal (Boolean)

System heartbeat. It toggles every second. It can be used to determine whether the communication connection between the PLC and Mech-MSR is normal or disconnected.

0.1

Trigger acknowledge (Boolean)

When Mech-MSR receives the rising edge of the Command Trigger signal, this signal is set to 1. When the command trigger signal falls, this signal is set to 0.

0.2

Data ready (Boolean)

Mech-MSR writes data to the output port and waits for the PLC to read it. When the Data Read Finished signal is 1, this signal is set to 0.

0.3

Command execution completed (Boolean)

When command execution ends, this signal is set to 1, indicating that the command has been processed.

0.4

Reserved (Boolean)

Reserved field.

0.5

Reserved (Boolean)

Reserved field.

0.6

Reserved (Boolean)

Reserved field.

0.7

Error (Boolean)

When the status code returned by Mech-MSR is not 1, this signal is set to 1 to indicate an error.

1.0

Overall judgment result (Boolean)

The overall judgment result of the project. 1 indicates pass (OK), and 0 indicates fail (NG).

1.1~1.7

Reserved (Boolean)

Reserved field.

2.0~3.7

Reserved (Byte)

Reserved field.

Quality judgment rules must be configured for the project in the Output Management window of Mech-MSR, and the measurement items considered during quality judgment must be determined. Only after the configuration is complete can valid quality judgment results be obtained.

STATUS_CODE

Mech-MSR may return the following status codes:

Normal status code: 1, indicating that the command was executed successfully.
Error status codes: -1, -2, -3, -4, and -5. See Error Codes for details.

JUDGE

The quality judgment results of measurement items added on the Communication Output tab in the Output Management window are returned here. 1 indicates pass (OK), and 0 indicates fail (NG).

Up to 64 judgment results can be output at one time for a single project.

VALUE

The VALUE module can return the following data:

The measurement results of the measurement items added on the Communication Output tab in the Output Management window.
The values of numeric global variables read when the GetNumVar command is executed.

Up to 64 measurement values can be output at one time for a single project.

Is this page helpful?

Leave a feedback

Thanks for your support!

You can give a feedback in any of the following ways:

We Value Your Privacy

We use cookies to provide you with the best possible experience on our website. By continuing to use the site, you acknowledge that you agree to the use of cookies. If you decline, a single cookie will be used to ensure you're not tracked or remembered when you visit this website.

I accept

I don't accept