Key defination

Dear All

I am new user of MACH3. I have installed it and it is working very nicely. I have defined Emergency Switch as external input from parallel port pint11. Now my question is can i define Stop button externally? i.e. i want to stop the machine when i press stop button from externally. Input may be taken to pin 10. when i press this button machine will stop there and then by pressing Cycle Start button i can continue the cycle. the advantage is that it will never skip the current code which is running. while in pressing emergency button and then pressing cycle start machine will skip the current code and start from the next code. which will damage the material as well as tool also. Please suggest me what to do if i want to configure STOP button from externally.

Sanlee