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14.3 CIU 502
You can detect faults in CIU 502 by observing the status of the
two communication LEDs. See the table below and section
14.3.1 LED status
Fault (LED status)
Possible cause
Remedy
1. LED1 and LED2 remain off when the
power supply is connected.
a) CIM 500 is fitted incorrectly in the
Grundfos product.
Ensure that CIM 500 is fitted and connected
correctly.
2. LED2 for internal communication is
flashing red.
a) No internal communication between
CIU 502 and the Grundfos product.
• Check the cable connection between the
Grundfos product and CIU 502.
• Check that the individual conductors have
been fitted correctly, for example not
reversed.
• Check the power supply to the Grundfos
product.
3. LED2 for internal communication is
permanently red.
a) CIM 500 does not support the Grundfos
product connected.
Contact the nearest Grundfos company.
4. The ethernet LED1 is permanently red.
a) Fault in CIM 500 Modbus TCP
configuration.
• Check that the rotary switch SW1 is set to
1.
• Check that Modbus TCP IP address
configuration is correct. See section
on page
5. LED1 is permanently red and green at
the same time.
a) Error in firmware download.
Use the webserver to download the
firmware again.
6. LED2 is permanently red and green at
the same time.
a) Memory fault.
Replace CIM 500.
