Catastophic failure

[slychiu]

If the UCM and Keypads can communicate then the RS485 bus must be working, and the problem should be in the SCS and RIO only

Do you have RIO or IRIO? RIO and SCS use different RS485 drivers so perhaps these were damaged. You can try to check if the KA and KB of the 2 modules are shorted. with everything disconnected and power removed. If they are shorted then it confrms they are damaged, but if they are not shorted it does not mean they are not damaged

[Swiss-Toni]

I have already determined that the issue lies with the RIO & SCS (KA KB are not shorted).
I went systematically went through all the components and know that when the working RIOs and SCSs are connected they cause the problem & have stated the process of replacement for these parts.

[Swiss-Toni]

Since installation of the new version of comfigurator the system is no longer reporting that RS485 is having communication error with the RIOs & the SCS however two of the SCS were unusable which were replaced!