Mit FX2N C251 Help

Hi there,

New to the forum, so please excuse ommissions, mistakes etc.

I'm trying to get the C251 (A/B Phase counter) on a FX2N operational - actually, I don't care if it is operational or not, I just want it to do something.

I have checked that the little LED's on the PLC are responding to encoder pulses (they flicker), so I assume the hardware is Ok. The A signal is wired to X0 and the B to X1.

I am using GX-IEC 6.01 and cannot get C251 to display any value while in monitor mode - or even on the HMI (E300).

I have also tried using X0 as a pure "contact" - ie: the rung looks like:
M8000 X0
--||----------||-------------------------------------(INC D??)

I am soon going to be bald from pulling my hair out, so please help me if anyone can.

Thanks

Paul

Mits Fx2n C251

Hi,
you need to drive the counter with say M8000 to get it to work.



M8000 D100
-¦ ¦-----------------------------(C251)

the contact for C251 will open/close depending on value in D100 (32 bits)

Hope this helps.

Michael Bell said:

Hi,
you need to drive the counter with say M8000 to get it to work.



M8000 D100
-¦ ¦-----------------------------(C251)

the contact for C251 will open/close depending on value in D100 (32 bits)

Hope this helps.

Click to expand...

Does this work with IEC?

I suggest you read the FX programming manual concerning high speed counters - there are lots of do's and dont's

A few to be going on with;

Dont use any other HS counters in your program - (for now just use C251)
Dont use X0 & X1 anywhere at all in your program including for the counter pulses.

Remember it is a 32 bit counter so if you are using D registers it will use 2 consequetive registers (D100 means D100 & D101)make sure both are not used elsewhere.

The counter will only count when it is turned on ie M8000 (always on bit)
It needs to be reset too, it will not auto reset when turned off.

The counter will continue counting past its preset point if still being driven.

Hi Michael and the others,

I have tried to drive the coil of C251, but I constantly get a compiler error - C2018 Boolean variables must be used with coils.

I have also tried a "SET C251" and then get a C2017 Type Mismatch (obviously).

Anything else anyone can think of...

Thanks

Paul

Hi Goody,

Thanks for this. There do seem to be more don'ts than do's. I think I have followed all of them. I even have a simple two line piece of code that I download for test purposes, and even with only one network centered around C251 I can't get the thing to count.

Please see my other reply earlier in the thread.

Thanks

Paul

Hi Paul,

this might not be answer you are looking for, but hope this helps.

You are aware that C251 is A/B high speed counter and so on... I have IEC 6.10 and when I like to use other high speed counters e.g. C236 I need to use Mitsubishi function blocks.

Maybe you know these already, but...
Goto library pool=>right click=>Install user library.
Browse lib=>Locate file: C:\melsec\IEC\userlib\fx_erw.sul=>OK.
Goto libray pool=>FX_ERW=>right click=>open.
You can see how other high speed counter function block are made. Perhaps you can make own block where you use Block COUNTER32_M. Ccoil would be CC251...

I haven't test this, but hope this helps.

You do not need to install FX-erw, you can see tips from there. Counter32_M is located in Manufactures pou pool (At least IED 6.10).

Tmu

Hi Tmu,

You do not need to sound so gentle when you have solved my problem. This is a command I have never seen, so thanks for that.

Now I just need to buy a wig to replace my bald patches.

Regards

Paul