Mitsubishi Q Motion

[mrtweaver]

I need some help decoding what someone else had written. It is in a Mitsubishi Q series platform. It is in the motion controller which happens to be a Q173HCPU, and it is connected to a Q173PX (pulser/encoder) card. Anyway i have decoded much of the information in the SFC program, but the one thing that i have not yet found is a command that is outside of one of the function blocks. It is a block that zeros one of the 3 counters in the motion control card. The command is IFB1, makes it sound like an IF B = 1 but not sure. SO i am hoping one of the mitsubishi gurus on this site can help me understand what this command is and what it is doing?


Also i was wondering, i am writing a new section to the program, and i am going to use counter 3 which is currently not used, if there a command i can use to monitor the one input to the counter and if that input goes to an active state, then i will do something? If so how would one compose such an action?


Thanks for your time.

 

[mrtweaver]

I do have one other question concerning the above mentioned hardware. This one pertains to the voltages for the 173PX card, i have not found a definitive manual yet for it but the one manual i did find says that the voltage for low level is 1v or lower and the voltage for high is 3v or higher. But there is not a clear notation of what happens if the voltage falls between the 1 and the 3. Is that a grey area where sometimes it might be read as 1 and other times a 0?

 

[drbitboy]

...s that a grey area where sometimes it might be read as 1 and other times a 0?

Yes it can be 0 or 1 but no it is not a grey area, because 1v and 3v are the thresholds of a hysteresis cycle.

Stated less ambiguously, the state will only change from 0 to 1 when the voltage goes above 3v, and will only change from 1 to 0 when the voltage goes below 1v; when the voltage is in between those thresholds, the state will not change from the value assigned the previous time it was outside those thresholds.


It may not be a Schmitt Trigger, but the behavior (hysteresis) is the same.

 

[mrtweaver]

If what you say is correct and that the behavior (hysteresis) is that way then that would mean if the pulse does not cross over those lines then the input would not switch. So in this case the one input is tied to the A pulse the other is tied to the Z. As the A is pulsing the counter is counting. And when it sees the Z it is to zero the counter.


However that zeroing does not always occur. So if you were to spin the encoder say 10 time around, it might zero and work properly 6 time, the other 4 times it would not zero out and would just keep counting.


And if it is this zero pulse, which is what i am leaning towards there are only a few things it could be.


First it could be the electronics inside the encoder might not be pulling the input to the right level. But that would mean that it should also be on the A pulse but that one just seems to click and count right along.


Second it could be timing in the PLC, maybe the input is not staying on long enough.


I am thinking there should be more things why it might not work but just not sure.


Mitsubishi asked that we try a different encoder said the problem might be in the encoder. But out of 4 encoders 3 do not work consistently and 1 does, does not seem like its the encoder. But again i could be wrong.


The 4 encoders are as follows: 1 older blue colored Dynapar, 1 newer black colored dynapar, 1 newer Pepperl & Fuchs, and 1 newer Mitsumi. Out of these four the only one that works consistently is the older blue colored Dynapar. Been back to Dynapar to ask about difference they say output drivers same, they only changed bearings and a few other things, so they are stumped. Even the maker of the PLC is stumped. And i know the answer is lieing right there in front of me i just can not seem to get to it. Which is why i am asking for ideas, thoughts, suggestions from this group.


Just as an FYI the things that have been changes: Encoder or course, wiring back to PLC, 173PX card, Q173HCPU card, so i am extremely low on ideas.


Thanks again for your time.