Hi Rob,
My email is rob@2hippo.com
Drop me an email and I will send you through all the details I have.
Regards
Rob
Hi All.
Rob193592 original problem with Rotary encoder has been basically solved.
Rob sent me some more details re his problem getting a rotary encoder to communicate with a PLC.
Firstly the first encoder he received had incorrect wiring details which effectively placed the 24V supply directly across one output transistor. End of that encoder as soon as he rotated it.
This seemed to lead to some confusion for Rob in any further experiments.
Once I had the information forwarded things became much clearer, particularly as the PLC had a remarkable resemblance to Mitsubishi units I had extensive experience with in the past.
These PLCs have a completely isolated input circuity (opto coupled) and can operate either source (PNP) or sink (NPN) configuration with the common for all inputs brought out to a connection designated “SS”. If this “SS” is connected to supply (24V) negative the inputs expect a 24V positive (PNP sensors) to activate. If the “SS” is connected to supply positive the inputs expect a connection to 24V negative (ground ???) (NPN sensors) to activate.
Rob has NPN open collector output Rotary Encoders, The PLC was configured to accept PNP output Rotary encoders.
The solution… Move the “SS” connection to 24V positive. The Encoder is now reported as working.
Simple ?? But could be a trap easily overlooked. Particularly as the manual for these PLCs is some 300+ pages, a fair percentage devoted to programming techniques. The corresponding Mitsubishi manual from memory was 328 pages. Little snippets like the above scenario can be easily missed.
I hope this might help others.
Cheers Bob
