If the E5600 meter is installed in switchgear, it is possible to install the communication cable wire harness upside down. The E5600 meter can only communicate if the wire harness is installed the correct direction even though it is possible to install the wire harness upside down if you push hard enough.
The symptoms of this issue include the fact that all the settings in the software are correct. The Tx and Rx lights will not blink at all. The meter will communicate through the optical cable but not RS-485. When the switchgear is opened the communication cable can be very difficult to remove from the meter.

To resolve the issue, flip the communications cable 180 degrees such that the cable is then right side up. This will resolve the communications issue, and the Tx and Rx lights will begin flashing.