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Issue:
Function block to use in a Premium PLC for retrieving diagnostic information from a Modbus slave device
Product Line:
Premium PLC, Unity Pro
Resolution:
The SEND_REQ function block is used for retrieving diagnostic and maintenance information from a Modbus slave device....
Function block to use in a Premium PLC for retrieving diagnostic information from a Modbus slave device
Product Line:
Premium PLC, Unity Pro
Resolution:
The SEND_REQ function block is used for retrieving diagnostic and maintenance information from a Modbus slave device....
Modbus Request | Function Code / Sub Function Code | Communication Function |
---|---|---|
Exception status | 16#07 | SEND_REQ |
Diagnostics | 16#08/16#xx | SEND_REQ |
Event counter | 16#0B | SEND_REQ |
Connection event | 16#0C | SEND_REQ |
Slave identification | 16#11 | SEND_REQ |
The diagnostics and maintenance information are shown below:
Designation | Function code / sub-function code |
---|---|
Read exception status | 16#07 |
Echo | 16#08 / 16#00 |
Initialize module | 16#08 / 16#01 |
Read the diagnostic registers of the PLC | 16#08 / 16#02 |
Change end of frame delimiter (ASCII mode) | 16#08 / 16#03 |
Switch to listening mode | 16#08 / 16#04 |
Reset counters | 16#08 / 16#0A |
Number of messages received without CRC error | 16#08 / 16#0B |
Number of frames received with CRC error | 16#08 / 16#0C |
Number of exceptional responses | 16#08 / 16#0D |
Number of messages addressed to the PLC | 16#08 / 16#0E |
Number of broadcast messages received | 16#08 / 16#0F |
Number of correct responses | 16#08 / 16#10 |
Number of messages received in listening mode | 16#08 / 16#11 |
Number of invalid characters received | 16#08 / 16#12 |
Read event counter | 16#0B |
Read connection event | 16#0C |
Read identification | 16#11 |