Check this out! Do you wire your e-stops to a standard (non Safety) PLC or controller in order to comply with the mandatory category 0 or 1 stop? Think twice is my advice! Yes, the safety standards such as NFPA 79, 9.2.5.4.1.3 require that an e-stop "shall function as either Category 0 or a Category 1 stop". These are stopping categories. Furthermore, your required risk analysis may require mitigation of a risk or hazard identified as Cat. 3 or 4. These are categories of risk. If you're wiring direct to a standard PLC your e-stop may only be at best achieving Cat. 2 or less so my advice is to check your risk analysis thoroughly.

Has anyone ever encountered this problem?