Grundfos CIM 200 Functional Profile And User Manual page 50

14.1.2 CIM 200 Modbus communication faults
Fault
1. The slave does not
respond to telegrams.
2. The slave responds with
exception response 0x01:
"Invalid function".
3. The slave responds with
exception response 0x02:
"Invalid data address".
4. The slave returns data
value 0xFFFF (65535).
5. The slave does not
change Modbus
transmission speed with
register 00004.
50
Possible cause
a) Configuration or wiring error.
b) The slave may be in listen-only mode.
c) If the holding register of address 00001
"SlaveMinimumReplyDelay" is set too high,
the master may time out before receiving the
response from the slave.
a) The master is trying to use an unsupported
function in CIM 200.
a) The master is trying to read or write an invalid
data address. If a master tries to read register
addresses that are not listed in the tables, the
slave will respond with this exception
response. Some masters may automatically
try to read large blocks in one telegram, which
will cause problems if some of the registers in
the block are not supported. An example
would be reading the CIM configuration and
CIM status blocks in one telegram. This is not
possible since there are unused addresses
between the blocks.
a) The value is unavailable. A data value of
0xFFFF does not necessarily indicate an error
condition. It means that the value is
unavailable from the Grundfos product.
a) Configuration error.
b) An invalid value may be set in register 00004.
Remedy
• Check the visual diagnostics on the Modbus
slave. Is the Grundfos GENIbus LED flashing
green and the Modbus LED off or flashing green?
• Ensure that the cable between the Modbus
master and the Modbus slave is connected
correctly. See section
5. CIM 200 Modbus RTU
for wiring recommendations.
setup
• Ensure that the slave address is configured
correctly, and that the correct slave address is
used in the Modbus master poll. See section
5.3 Modbus address selection
selection.
• Ensure that the transmission speed and stop bit/
parity settings are configured correctly in both
master and slave.
• Ensure that each end of the Modbus trunk cable
is terminated, if necessary. See section
for line termination of the
5.4 Termination resistor
Grundfos slave.
• Ensure that the bus topology for a Modbus
network is correct.
Either send a restart communications diagnostics
command, or restart the Grundfos product
manually.
Increase the timeout span in the master in order to
communicate.
See section
8. Modbus function code overview
supported function codes. Note that reading and
writing coils are not supported, so only register
functions and diagnostics are valid.
• Avoid reading or writing invalid data addresses.
• Ensure that register X is addressed as X - 1 in
Modbus telegrams, according to the Modbus
standard.
See section
10. Modbus RTU commissioning, step-
for available data.
by-step guides
Set the transmission speed switches to "Software-
defined". Otherwise, the value in register 00004 is
ignored by the slave.
See section
5.1 Setting the Modbus transmission
for invalid values, and set correct value in
speed
register 00004.
for slave address
for