Not a bug

Overload on MC43FS DOUT HS+LS Channel

Richard Staite 6 years ago in IQANdesign updated by Zach Dockter 6 years ago 2

We are working on an application where we are required to be able to allow parallel operation of a solenoid valve. i.e. to be able to energise the solenoid via external means at times. We had been intending to get around the error detection problems by placing these outputs into a function group which we disable when the external energising  happens. This seems to work fine for open load detection, however overload still seem to be detected even when the channel is not enabled -is this intended or is it a bug?

Not a bug

This is intentional. 

The lower layers on the MC4x will keep diagnosing the outputs even when the application have them disabled. 

If you parallel operate the load with some other system when the DOUT is off, you will see overload from low-side short to ground, and overload from high-side connected to ground via the load. 

If you parallel operate the load when the DOUT is on, you will see open load from the undercurrent detection. 

Parallel operating also means you can reverse feed the module, this is detected on startup. 

See Appendix B, section "Failure modes, external faults on power drivers"


So is there a way to run a parallel, hardwired operation like what Richard is asking?

I'm doing the same thing, powering an alarm, I need a physical wire and I need it through the PLC, I used diodes but it throws an error.