IEC 61131-2:2017 specifies functional and electromagnetic compatibility requirements and related verification tests for any product where the primary purpose is performing the function of industrial control equipment, including PLC and/or PAC, and/or their associated peripherals which have as their intended use the control and command of machines, automated manufacturing and industrial processes, e.g. discrete, batch  and continuous control.
This fourth edition cancels and replaces the third edition published in 2007. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
a) removal of safety requirements and instead pointing to IEC 61010-2-201;
b) addition of negative logic digital inputs and outputs;
c) addition of Type 3-d digital input;
d) addition of 2,7 GHz to 6 GHz requirement for Radio-frequency electro-magnetic amplitude modulated immunity;
e) clarification of temperature testing;
f) clarification of type testing;
g) deprecation of certain technologies;
h) general update of multiple aspects of functionality and EMC;
i) reorganization of clauses to associate requirements and verifications more closely.