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Messages - Mark P.

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1
Technical support / Jog Moves with Step / Dir
« on: March 08, 2019, 01:16:38 PM »
Hello

I have an application that uses Step and Direction on the FX processor.

All works great, but I need something a bit different than the standard commands ?

Let say my stepper motor is running a fan.    It really has no distance

I just want to run it and adjust the speed while in motion.

Basically a jog command with speed change.

My concern is all the move Commands seem to have a distance associated with them.

I don't want the fan to stop eventually when it reaches the upper limit of move commands, just turn.

Is there a way to directly control the pulse train out ?

Thank you for any thoughts

Mark

2
Technical support / Reading Mechanical Encoder
« on: February 28, 2019, 11:09:44 AM »
Hello

I have been having a problem reading a mechanical encoder.

That is, a mechanical encoder not a normal encoder like on a motor.

I have tried high speed encoder in, that did not really work.  Skips or jumps.
I am guessing the signal received from a hand turned encoder knob is not the best signal.


I have written some code to look at the inputs and make decisions if the encoder went right or left
based on inputs and previous inputs.   This seems to work best but there are times this is not perfect either.

I have probably spent a week trying several software iterations and different encoders, and different inputs.

Has anyone taken in this type of encoder that worked almost flawlessly ?

I also think scan my also be causing a issue ?  Missing inputs ?

Also these encoders come in several types of code output, I prefer a two wire
method, that is useing just two inputs.  Don't have enough inputs available to 4 wire gray code.

Any suggestion on code or encoder brand or type would be helpfully.

Mark

3
Technical support / Trouble Reading FP Values
« on: January 27, 2019, 06:52:28 AM »
Hello

I am trying to Modbus Read some FP values from FX processor.
I am reading them from another FX processor.
Reading DM values works fine between the two.

Maybe the number system is off in the manual or these need something special ?

tIf looks like if I want to read FP[1]  the modbus values are held in 5000 and 5001

No matter what value I put in FP[1] greater then Zero I always get

in 5000 modbus location =16256 and  5001 =  Zero ?

Basic read code

C# = READMODBUS (13,2,5000)  'READ Value from Aux 2

D# = READMODBUS (13,2,5001)  'READ Value from Aux 2


This code works fine Reading DM values work fine with numbers like 1000, 1001 etc.
I have tried server variables to put the data in, no noticeable change

Am I looking in the wrong place for FP values ?



4
Technical support / Stepper Stepping Bit ?
« on: January 13, 2019, 07:52:24 AM »
Hello

I have an application where I am useing several stepper functions.

All work well but I am in need of some way to know if the stepper output is putting
out pluses in the logic.

The really available on the STEPMOVE or STEPMOVEABS are very unreliable.

I have tried to look at the output that is stepping in the logic but at least a rung level it shows
nothing while stepping.

Any thoughts ?

If output pluses are being put out of output would like to know.
And turn this into a bit (stepper stepping)

Possibility there is some memory location behind the scenes I could look at ?

Thank you

Mark

5
Technical support / Re:Mobus Writes Blocking PLC inputs
« on: January 13, 2019, 07:45:39 AM »
Thank you !

Glad at least there's a logical answer.

To accomplish some of your suggestions

#2 Perform only a single Modbus operation per ladder logic scan.

#3 Ensure that between Modbus operations that the ladder logic is allowed at least one scan of the ladder logic.

Can I do something like :

inside of Dfuction block.  

x=x+1

if x=2 then
writemodbus ***
endif

If x=4 then
writemodbus ***
endif

etc...  etc..

If x >10 then
x=0
endif

I am assuming every scan it will increase x by 1.

Thank you again

Mark


6
Technical support / Mobus Writes Blocking PLC inputs
« on: January 12, 2019, 08:49:39 AM »
Mobus Writes Blocking PLC inputs

I know this sounds crazy but I have seen it now with two different programs on two
different FX processors.

What I am doing is writing from one FX master to one FX slave

The master has the program and it seems to send data well.   But depending on the number of writes or where
this is done in the program effects the rungs below it.

It works best when put at the very bottom of my program and worst at the top.

I am guessing that the Modbus writes are taking up too much scan time and blocking other functions in the FX Processor.

Unfortunately this is causing problems.

I have seen when the Modbus Read is at the top, the input light on the board come on, when monitoring It wont be seen
and the logic will not execute.   Block the Modbus Write rung and all works correctly.

How quickly can dCust functions containing something like WRITEMODBUS 13,2,1263,DM[11] be plused ?

How many Writes or Reads should be inside of one dCust ?

Should you use dCust or some other function holder ?

Should the Status bit be used in the rung of function for added reliability ?

Any other thoughts ?

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