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Default Unit ID, Function Codes and Parameters can be found in the datasheet for the specific product. Answer messages are structured similarly and should be described in the product-datasheet as well.
Configuration
Sub-menu: /iot modbus
Once the board is connected to the Modbus device, check "modbus" port configuration (baud-rate can be changed if the connected Modbus device expects another value):
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Additionally, when you want to allow Modbus clients to communicate with the Modbus server using TCP(502)/IP protocol, you need to make sure that the IP address is configured accordingly and that this IP+502 TCP port is accessible from the outside (in case "slave" devices are connecting from the WAN side). You can find information on how to configure the firewall using the firewall manual.
| Property | Description |
|---|---|
| disabled (yes | no; Default: yes) | To enables or disable Modbus functionality. |
hardware-port (list of string; Default: modbus) | Assign a port to the service. Use the default "modbus" port. |
| tcp-port (integer:0..4294967295; Default: 502) | Specify the TCP port that the device will use for Modbus TCP communication. |
| timeout (integer:0..1000; Default: 1000) | Specify the timeout value, in milliseconds. The time, during which Modbus request is sent, and the reply is received. If the time between the request and the reply is longer than the configured value, the "failure" is returned. |
| disable-security-rules (yes | no; Default: yes) | To enable or disable security-rule feature. |
Sending function code commands via Modbus RTU
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