I am trying to find either a portable or bench frequency calibrator to be used as an input to a PLC DC input card or device. I am trying to simulate a open collector type pulse signal (flow sensor pulse output into a PLC input). The PLC requires a 14V minimum signal in order to register. The frequency I need needs to be adjustable. Approximately 1-1000 HZ but higher frequency range is fine. The nominal impedence of the PLC input is 3000 Ohms. I have tried to find a vendor with this type of device but the 14 volt minimum seems to be a problem. My application is using a AB Micrologix 1000/1500/or 1746-ITB1. Does anyone know of any frequency calibrators that could do this? Thanks a lot.

 

We use a BK Precision Model 4011A Function Generator to do that very thing.

We have used it on both a Micrologix 1200 and SLC 5/04 to simulate flow pulses.

 

How about a couple of 555's or a 556 for a buck or so. on an 18V power supply (two 9v batterys in series) it should work great. One is a monostable to set pulse width and the other sets the frequency and triggers it. I'd check test-equip and the other used equipment vendors. Any older pulse generator should do this. My $500.00 scope has a generator built in that will do that. You're just looking in the wrong places. I'll send you a 555 drawing if you want, free.

Regards

cww
--
Free Tools!
Machine Automation Tools (LinuxPLC) Free, Truly Open & Publicly Owned Industrial Automation Software For Linux. mat.sourceforge.net.
Day Job: Heartland Engineering, Automation & ATE for Automotive Rebuilders.
Consultancy: Wide Open Technologies: Moving Business & Automation to Linux.