VFD control with uac-cx-01rs4 port setup as Modbus panel

[RBC]

Hi.  We have  temp / hum sensor, valve controller and  damper controller with unitronics vfd connected to unistream plc.  We have trouble with network if we read and write to the valve and vfd.  If we only write it seems to be working but as soon as we read a value the we loose connection or control of the vfd.  The modbus 485 comm port is added to the plc.  It caanot be set up as vfd port then the other modbus units does not work.  So the port is setup as modbus panel.  All setting correct as we can write the freq of the drive as needed.  It's only if you want to read as well write that problem start.

 

Any ideas please.