Using a Thumbwheel to Input a Program Number

I hope this isn't off topic, I'm losing my mind over this problem and the Arduino forums have always been super helpful.
I am working with a Scara robot that has an industrial controller (IAI-XSEL), and what I'm trying to do should be incredibly simple but for whatever reason I can't get it to work.
The controller has 7 program specification input ports to allow for an external device to call a program number (see attached image for details). I just want to use a very basic BCD thumbwheel (C&K - 302109000 - Switch,Thumbwheel,Decimal,BCD,10 Position,Snap-In,Front Mount,Type 0 Termination - Allied Electronics & Automation) to allow for an operator to easily select a program. I need about 30 programs, but there are only 10 positions on the thumbwheel so I am using two thumbwheels and I think that should get me a max of 99 programs.
I have C on both thumbwheels connected to the same +24V as the controller. For the first thumbwheel I have 1 connected to input 7, 2 connected to input 8, 4 connected to input 9, and 8 connected to input10. For the second thumbwheel I have 1 connected to input 11 and 2 connected to input 12, 4 & 8 are not connected because I don't need that many numbers and I don't have enough input ports.
I can monitor the status (whether it's a 1 or 0) of each input to the controller from my PC, and for whatever reason it's not reading any inputs from the thumbwheels, all of the inputs just stay low. Am I just fully misunderstanding something fundamental? I've verified that the input ports work and the thumbwheels work (with an Arduino), I just can't get them to work together (and I haven't even gotten to the programming part :confused: ).
Thanks in advance for any help!

Maybe the inputs are low true (sinking) and you need to connect "C" to ground.

Thanks for the reply!
I did try that as well, but there wasn't any change.

Funny thing about almost all switches, including your thumb wheel switches, Is that between the detent positions, the switch is an open circuit. You need a scheme to ignore the switches until such time as there are no further changes in position, or a separate switch to tell you program to now READ the thumb switch settings.

Did you take voltage measurements on the port pins with only the original switch and decode them?
(convert to the base used by the machine to see if it matches the thumbwheel setting ?)

The manual is here: The connection diagrams are on pages 31 and 32,
but note that there are two versions, PNP and NPN interfaced, you have to know which you have.

Have you checked the pin out of the BCD switch with a meter by hand? (always worth doing BTW,
many parts come in variations and its the only way to be sure you have the right version). Also
I think you might be confusing signal name(1,2,4,8,C) with pin number (3,5,7,11,9)

Have you thought to monitor the input voltages directly with a meter while operating the BCD switches?

This topic was automatically closed 120 days after the last reply. New replies are no longer allowed.