I’m new to Delta controllers so I have a simple setup with a hydraulic test bench. I have a hydraulic cylinder being controlled by a proportional directional valve and have a LVDT signal for position feedback. The LVDT rod has 0-10V output for position feedback. I have the 0-10V position feedback wired to the analog input 0 on the rmc150e. I’m getting correct voltages at the controller measured by a voltmeter however in rmc tools I have a indirect variable displaying the analogs voltage input and it is not displaying the same as my meter at the delta inputs. If I move my LVDT rod the variable seems to follow the input at a much smaller scale. For example at position 1 of my setup I read 5vs with my multimeter directly measured from the analog input 0 terminal, however the RMC tools analog voltage on that axis (axis 2, as I have a SSI card in first slot and the analog card in second and I’m connected to first input, using default axis definations which I double checked) is displaying approx. 4.3Vs. When I move LVDT to position 2 I’m reading 8vs at the delta terminal with my multimeter but only about 5Vs in RMC tools. Is there something in RMC tools that scales the input? Also upon I noticed that I have strange voltages on other inputs on the terminal of the card with no wires connected at all. Am I seeing backfeed from the backplane of the card or is something wrong with my analog card or delta RMC150E? Any help would be appreciated. Thanks in advance
The analog inputs have internal biasing that pulls the input down to a bit below -10 V, in order to detect a broken wire. This is why you are seeing the strange voltages with no wires connected. If the driving circuit from the sensor is too weak (it has to be really weak for this problem to occur), it may cause the RMC to read incorrect values.
How about if you connect a battery or variable voltage power supply to the input terminals, how does the RMC report the voltage then?
Make sure that the Input- and the Cmn are connected to each other. For best noise immunity, the Input- and the Cmn should be connected to each other as close to the transducer as possible, and the Input- and Input+ wires should be twisted, shielded pair.
What is the make and part number of your position sensor?
thank you for your help. I found that if I take my input - directly back to my 24v common It fixes the issue and works perfectly