Do the serial ports on my MVI56 module provide any electrical isolation?

The two application serial ports provide 1000 volts of electrical isolation between the port and the ControlLogix backplane.
The debug/configuration port provides no electrical isolation.

Note: None of the ports provide any electrical isolation between the port and the module's internal circuits.
In installations where ground loops, floating grounds, multiple grounds, or multiple sources of power may be present for devices connected on the same physical network, it is advisable and highly recommended that the end-user provide some form of electrical or electro-optical isolation between the module's application serial ports and the communication network cable to protect the module from potential electrical damage.