BIN instruction faulting PLC

[coxbd316 0]

Hello everyone, First time posting, but I have been following the boards for awhile. Breakdown of what I have is an A1SH PLC on a piece of equipment that have 2 Omron thumbwheels used for Model #'s. The code I am using to get the model # in the PLC is this: PLCfault.bmp My problem is when you flip through the thumbwheels real quick, it faults out the PLC. But if you don't flip through the thumbwheels quickly then the PLC doesn't fault out. As anyone seen this before? Thanks for your help!!

[Sergei Troizky 26]

X18 input address is illegal in Mitsubishi. Inputs/outputs addresses are octal, hence cannot contain digits 8 and 9.

[coxbd316 0]

Thanks for the reply, I'm pretty sure Mitsubishi input/output designations are in hex. Which would be 0-9 and A-F. Don't believe that is the issue.

[kaare_t 155]

Sure Mitsubishi A and Q series are in hex, only the FX-series uses octal addressing, so that is not the problem. Can you tell us a bit more about your setup? Which/how are your cards set up? Is this the first input card, and what card comes next?

[Crossbow 296]

He said A1SH, which addreses in HEX, so 8 and 9 are valid inputs. Only the FX models address in octal. How do you know that command is causing the fault? Have you verified the error code and the step number? And have you looked at what about that instruction could possibly cause that error in the programming manual? It will indicate for each command what PLC errors can happen. IB(NA)66250 clearly indicates the only error this command can cause is if the value input exceeds 9999. So an invalid string of bits is coming from the thumbwheel.

[waynes 8]

Good point crossbow, But it would not be possible to get a value higher than 99. (K2X18) Only other thing is that the nibble inputs are not within the 0-9 range. 0011 1111 = 3F which would be invalid where as 0101 1001 = 79 and is valid. The problem you are experiencing is an electrical one. What you could do is delay the reading of the BIN inputs by checking when one of the bits in the K2X18 range (X18-X1F) changes. Edited 4 Feb 2010 by waynes

[coxbd316 0]

Thanks for all your info. As per Crossbow suggestion, I took a look at the IB(NA)66250 manual and ran across this: BIN_Manual.bmp It is stating that an operation error can occur due to BCD switch timing. What I am thinking is when the operators of the machinery changes model numbers on the thumbwheels, the are flipping through the thumbwheels quickly so this BCD switch timing must be setting off the operation error. Waynes makes a good point as to delaying the reading of the BIN inputs, but I believe the best answer would be to have the operators change their model # on the thumbwheel, then press a button to do the reading of the BIN inputs. Thanks everyone for your responses and help.

[Crossbow 296]

Typically the press a button to read method you mention is used. Let them dial up all they want, and then hit enter to proceed. Or perhaps tie it the PLC's 1 second clock pulse so the command only runs once per second.