The PLC does not specify "EMI requirement" because EMI requirement is stipulated by the industry that your equipment is supposed to serve. For example, on board ocean vessel, on board aircraft and medical equipment there are different bodies governing the requirement. It is for you to test your equipment (not only the PLC, but the entire equipment) to be able to conform to their requirement. There are many aspect of EMI, it could be its tolerance to external EMI or whether your equipment generate EMI that may interfere with other equipment (such as the requirement of FCC Class B Part 15).
Our PLC has been tested to work when subject to EFT interference (Electrical Fast Transient) up to 2KV (on Power Supply), 500V-2KV (on I/O), 50ns pulse width. This is in line with the IEC801-4 (1988) specifications for EFT interference test.