13.6 Diagnostics, 0x08
Only supported by CIM 200 Modbus RTU.
This function provides a test for checking the communication
system between the master and the Grundfos slave. It contains a
single-byte subcode to identify the test to be performed.
The following subcodes are supported:
Subcode Name
0x00
Return query data
Data in this request are to be echoed in the response. The
response must be identical to the request, so this function is
often used to verify Modbus communication.
0x01
Restart communications
All communication counters are cleared, and the device is
restarted.
0x02
Return diagnostics register
Returns the 16-bit diagnostics register.
0x04
Force listen only
Forces the device into listen-only mode. This effectively mutes
the device, making it unable to communicate on the network.
To bring the device back to normal mode, a "Restart
communications" command, code 0x08, subcode 0x01, must
be issued.
0x0A
Clear counters and diagnostics register
Clears all counters and the diagnostics register. These are
also cleared on power-up and restart.
0x0B
Return bus message count
Returns the number of messages detected by the slave.
0x0C
Return bus CRC error count
Returns the number of CRC errors in the slave.
0x0D
Return bus exception count
Returns the number of Modbus exception responses that the
slave has transmitted.
0x0E
Return slave message count
Returns the number of messages that the slave has
processed.
0x0F
Return slave no response count
Returns the number of messages for which the slave has sent
no response.
Example of request from master to slave
Field
Value
Address 0x01
Function code 0x08
Subcode 0x00
Data 0xAB
Data 0xCD
The response is identical to the request.
Example of response from slave to master
Field
Value
Address 0x01
Function code 0x08
Subcode 0x00
Data 0xAB
Data 0xCD
Related information
13.7 Diagnostics register interpretation
13.7
Diagnostics register interpretation
The diagnostics register is interpreted as follows:
Bit Description
0 Communication failure, with the Grundfos E-pump.
1 RESERVED
2 Grundfos E-pump is not supported.
3
Modbus address offset is different from default value, i.e. it differs from
0.
4 Using software-defined Modbus transmission speed.
5 RESERVED
6 RESERVED
7 RESERVED
8 RESERVED
9 RESERVED
10 RESERVED
11 RESERVED
12 RESERVED
13 RESERVED
14 RESERVED
15 RESERVED
A bit value of 1 means true, unless otherwise specified. The
diagnostics register is read using function code 0x08 and subcode
0x02.
13.8 Diagnostics: return query data
This function is useful to ensure that the communication path and
slave configuration are correct. It will echo the request in the
response.
In the example, slave address 0x01 is used.
Request from master to slave
Field
Value Description
Slave address 0x01 -
Function code 0x08 Diagnostics
Subcode 0x00 Echo request
Data 0xAB Test data
Data 0xCD Test data
Example of response from slave to master
Field
Value Description
Slave address 0x01 -
Function code 0x08 Diagnostics
Subcode 0x00 Echo request
Data 0xAB Test data
Data 0xCD Test data
If there is no response from the slave, see section Fault finding.
39
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