Why does my RS-232 S-Bus communication not work with the PCD2.F2xx0 and PCD3.F2xx module?

FAQ #101775

 

Symptom
Due of a Firmware error on the PCD2.F2xx0 and PCD3.F2xx module (with Firmware of the PCD2.F2xx0/PCD3.F2xx module: less or equal V020) it may be, that the S-Bus communication over converters (like modem or optical converters) to other devices does not work.

The S-Bus communication works fine, if no converters are used in between.
Also other communications protocols then S-Bus like "Mode C, Modbus" works fine on the PCD2.F2xx0 and PCD3.F2xx module (with and without converters in between).

On the print screen below, the signal 1 is RTS and signal 2 is the dataflow.
With PCD3.F121, the RTS signal behaves correctly, with PCD2.F2xx0 or PCD3.F221 not.

Communication with PCD3.F121


Communication with PCD3.F221


Workaround to use the RS-232 S-Bus communication over converters:
For the PCD3:
Instead of using a PCD3.F221, use the PCD3.F121.

For PCD1.M2 or PCD2.M5:
Instead of using a PCD2.F2xx0, use the PCD7.F121S.

Solution
The Firmware version 1.xx.xx of the module PCD2.F2xx0 or PCD3.F2xx will solve this bug with the handling of the RTS signal. Please contact your local SBC Support center.