mmervenne Posted January 25, 2006 Report Posted January 25, 2006 (edited) I am wiring a String Pot to a FX2N-4AD. I am having a problem getting a reading so i wanted to make sure i have it wired correctly. I have String Pot Wires FX2N-4AD + Input--------------------V+ Common----------------- 24- + Output------------------V- I am new to mitsubishi. Any help is Greatly Appreciated. Thanks Mike Edited January 25, 2006 by mmervenne Quote
panic mode Posted January 25, 2006 Report Posted January 25, 2006 i'm not sure what is string pot but if i was doing it, i would first connect 24V to power terminals of the card, get small regulated 10V power supply, connect ends of pot to it (10V), and the wiper from pot to plc analog input (V+), and of course connect commons. all of this can be seen on "page 2 of 12, Terminals layout" in manual http://www.meau.com/Files/JY992D52601-E.PDF, if the link above doesn't work, try this: http://www.meau.com/functions/dms/getfile....000000205601000 you may also want to read this: http://www.meau.com/functions/dms/getfile....000000206602000 Quote
Colin Carpenter Posted January 25, 2006 Report Posted January 25, 2006 What are you trying to achieve with the Pot? The FX2N-4AD, as far as I am aware, can only be configured for A/D conversion of either mAmp inputs or 0-10 volt inputs. A potentiometer is a variable resistance, so are you using it to try and alter voltage or current? What have you got the channel configured as? mAmps or Voltage? Questions, questions, questions ...... Quote
mmervenne Posted January 26, 2006 Author Report Posted January 26, 2006 [The String Pot is used to measure position. it is a pot with a cable attached to it, the other end of the cable is attached to an actuator. as the actuator moves it pulls the string, changing the resistance, therefore changing the voltage i read back. I had a bad string gauge, thats why it wasnt working. I replaced it and it is working fine now. The only problem is i am having a problem getting the readback scaled to a floating point number. I would like to scale the input to reflect actual position. Does anyone know how i can get a floating point number? quote name=Colin Carpenter' date='Jan 25 2006, 08:31 AM' post='27367] What are you trying to achieve with the Pot? The FX2N-4AD, as far as I am aware, can only be configured for A/D conversion of either mAmp inputs or 0-10 volt inputs. A potentiometer is a variable resistance, so are you using it to try and alter voltage or current? What have you got the channel configured as? mAmps or Voltage? Questions, questions, questions ...... Quote
Crossbow Posted January 26, 2006 Report Posted January 26, 2006 What PLC are you using with this FX2N-4AD? You should be able to use a command in the PLC to convert the integer to floating point, and then do floating point math to scale it. Use FLT to convert the Int to FP, then use EADD, ESUB, EMUL, and EDIV to scale it. be sure to check the programming manual JY992D88101D for help on these commands. It's in the MRPLC.com downloads section. Quote
mjrx Posted January 26, 2006 Report Posted January 26, 2006 I would put a resistor in series with the pot to the 24V+ to limit the pot to 10V. This value will depend on the pot value ( a 5K pot would require 7K of resistance to make a 0 - 10V swing). Quote
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