IR DD-158HFA Compactor, Electronic Control Module Replacement

Hey all, I am working on a Ingersoll Rand Dual Drum Vibratory Compactor. Model DD-158HFA. This unit was purchased right around 2006 or 2007, the owner has had a problem with it for years where for no reason the parking brake comes on randomly. Obviously they cant operate like that. The mechanics have troubleshot down through all of the switches and hydraulics and are stumped. The dealer, Volvo, is also at a loss and cant figure it out. Basically it looks like there is a random fault in the VANSCO Control Module that runs the whole machine. The dealer cant help and isnt able to get a new one due to the changeover from IR to Volvo.



What I am doing is taking out the Vansco unit and replacing it with a mobile hardened PLC, I have the manuals from IR and have figured most of the Inputs and Outputs. I have programmed the safety interlocks required. The only thing I am not sure of is the Vibrations per min signal, and what type of a signal is coming from the drum speed sensors.



I am assuming that the VPM signal is an analog signal from the controller to the gauge on the console, probably 0-5Vdc. The drum speed sensors probably output either a pulse output like an encoder or mag pickup, or an analog output, but more than likely a pulse output.



Any thoughts on these two signals?



Thanks,



Will