What does this mean (on GE Fanuc)

[1320]

On a ladder rung I have %Q0001 which does not relate to the output address on the PLC, what does it mean?

 

[1320]

Ok what I just figured out is %Q0001 relates to Output number 28, but I still want to know how the two are associated.

 

[rootboy]

%Q0001 is the first point in the output table. Because it isn't necessarily wired to anything makes no difference.

I'm not clear as to what output #28 is, is this something that is specific to your application?

Wait... Is this output actually attached to a coil, or is it part of some other statement? Please post that bit of your code if you would.

BTW, what programming environment are you using? Logicmaster or Versa Pro?

 

[TurpoUrpo]

Or Simplicity Machine Edition? (or is that same as Logicmaster or Versa Pro?)

 

[rootboy]

Or Simplicity Machine Edition? (or is that same as Logicmaster or Versa Pro?)

Yeah! That too. (I've only worked with the two that I mentioned, I had forgotten that there was other programming software out there).

 

[sumanthb4u]

On a ladder rung I have %Q0001 which does not relate to the output address on the PLC, what does it mean?

Can u explain ur problem clearly? as per my understanding i'm replying.

Check your hardware configuration. If the starting output is %Q00001 then the starting address will be %Q00001 in the PLC lader logic. If its starts with %Q00028 in the hardware configuration, then in the PLC logic u'll be giving %Q00028 address. For this,output-1 goes high if %q00028 goes high.

 

[tomalbright]

Although one can do it, I don't know why you would, you can assign a starting IO address to your modules. Normally, you would start the outputs at Q1. but it is possible to start anywhere in the "Q" files. I ran into this retrofitting a system. where the new additional input modules were thrown out of whack by the "I" tables being bumped by the ethernet module's status block.... which for some reason GE used "next available" on the block.

 

[rootboy]

Although one can do it, I don't know why you would, you can assign a starting IO address to your modules. Normally, you would start the outputs at Q1. but it is possible to start anywhere in the "Q" files. I ran into this retrofitting a system. where the new additional input modules were thrown out of whack by the "I" tables being bumped by the ethernet module's status block.... which for some reason GE used "next available" on the block.

This is true, you don't have to start at %Q0001, but if he has %Q0001 in the program, presumably it's assigned somewhere in the rack. Well, I would hope so anyways...

And being the 28th output isn't likely, since it isn't on a byte boundary + 1.

(although I know of one company that uses 3-1/2 byte wide input cards on their AGV's. Think of it as DINT lite ).

I think what he may be seeing is something like an XOR that zero's out the output table and the output that he is interested in happens to be the 28th output.

 

[cjd1965]

Hi
Sounds like Output 28 (%Q28) is slaved by %Q1 for some reason... maybe one is a valve, the other a pilot light for example....

ie %Q1 = call 'red valve' %Q28 'red valve called lamp'

cheers

Edit: After thinking about it, it may be a status word from an I/O card... check the configuration of all cards/cpu etc

 

[bkottaras]

Even though your %q28 is the actual output, if you haven't entered a description the software automatically assigns %q0001 as a descriptor by default.
Proficy ME does.
If this is the case, then your ouptut %q29 will have a descriptor of %q0002 assuming that whoever wrote the program used sequential ouputs.

 

[cjd1965]

Hi I never noticed that behaviour, but then i always program in logicmaster style (1q,1m etc) then add descriptions on the fly if required. If I dont do descriptions in advance or on the fly it can become difficult to remeber exact purpose somtimes. Also noticed rung comments can get stripped from program if u upload a 'not equal' program

Cheers

 

[rootboy]

Even though your %q28 is the actual output, if you haven't entered a description the software automatically assigns %q0001 as a descriptor by default.

This is kinda off topic, but you bring up a good point. There are some nasty tricks that you can do with a PLC.


At Spring Hill, the guy who translated the Series Six code to 90-30 for our Ube's had created nicknames that looked like the register in use, except that he made these nicknames look like a different register than what it really was (i.e. the nickname for %R1000 might show "%R2000" as its nickname).

He also setup ARRAY_MOVE instructions for 5000 & 32000 words (when he really didn't need to be using ARRAY_MOVE instructions in the first place). He usually didn't use more than 40 registers for any operation.

He would use this block for anything that he was controlling (PID, thermocouples, pressure, etc). He oneshot most of the array references so backtracking them was nearly impossible.

So he was essentially using nearly the entire register table to obscure what he was doing.

You could forget about finding an "unused" register, they *all* showed up in the search results.

And he would get the inputs to trigger the various ARRAY_MOVE operations externally (undocumented, of course) so that it was nearly impossible to figure out where things were coming from.

And on top of that he used BTST (Bit Test) and BSET (Bit Set) operations to trigger his logic.

And of course, his documentation was either missing or incorrect.

He did other tricks to keep people from figuring out what he was doing, but these were the worst.

I suspect that he thought he was going to be the only guy in the world who would be able to work on these machines.

Nope, not hardly. We got what we needed fixed. But I do have to hand it to him, he is the closest thing to an evil genius that I have run up against.