Hello,
I am working on setting up a tool change probe, I run ESS with a PMDX-126.  In control configuration under inputs I cannot seem to get the active low flag to stay set.  When Mach 4 is enabled the probe LED on the screen is lit and when I press on the tool change probe the led on the screen goes out.  If I press it more I get an e stop like I should.
Every time  I go back in and the setting for the probe to see if it active low it is set to active high.  Their must be some setting I am missing. 
Thanks for your help.
Todd

Have you checked the ESS settings?