In our systems we often use multiple Roboteq controllers with single micro-controller. High baud rate of nextgen serial communication is too fast for typical optoisolators, so we are using RS232 converters with ground pass-through. This means that logic grounds of all Roboteq devices are connected, creating dreadful ground loops, even though this ground is not connected to battery anywhere past RS232. Disconnected battery ground on any of the devices will pull high current trough logic pins of the others.
Question: is it OK to have logic grounds of multiple Roboteq devices to be connected to each other and to micro-controller powered from one of them? Do you have any suggestions for improving overall system safety for this kind of architecture.