CONNECTION TO THE MODULE IS BROKEN

[Vinod_Mathews]

i am using FP-1600 with DO-AC-240 after two or three write operation to the FP-DO-AC240 module field point explorer give the error "CONNECTION TO THE MODULE IS BROKEN".error message comes with FP-RLY-422 module also.why?

[Aaron_G]

Vinod,

Noticing that you are using both FP-DO-AC240's and FP-RLY-422's, I am assuming that you are attempting to switch AC voltage through the FP-RLY-422 module. I am further assuming that you are controlling an AC motor or solenoid or similiarly high inductive load. With high inductive loads, turning the power off results in a large spike of voltage, generated by the inductor (such as the solenoid) to be driven back along the circuit. These spikes, can have a number of effects on electronics. They can cause the the network module to temporarily lose communications with the I/O module, or in some cases can be so severe as to cause damage to a module.

If you were to measure the control lines with an oscilliscope, you are likely to see spikes that can be mo
re than 1000 Volts. We do have circuitry in the modules to help minimize the spikes (these spikes are known as back-EMF). Occasionally, however, the spikes are so large that our built-in protection is not enough. I recommend using an AC snubbing device such as a Metal Oxide Varistor (MOV) to reduce the back-EMF being seen in your circuit. Reducing the back-EMF will solve the temporary communications loss you are seeing.

Regards,
Aaron