Todd Dice (Customer) asked a question.
I need to code a Push to Set/Push to reset via one pushbutton. I have code I've used for decades BUT it is not retentive in power loss. Now, if I was coding a Click, then sure, just make the bit retentive (done it, works great!) However, I am coding the overpriced PLC from Milwaukee and need to use Latch/Unlatch bits. I looked in their "knowledge base" but their code is basically the same as mine without use of latch/unlatch.
I looked at example programs on automationdirect.com and found nothing.
I'm asking here because I swear I saw someone post how they did it in Do-more Designer and my search has been fruitless. Looking in Host's forum didn't do the trick either
If anyone can help I'd appreciate it. Thanks!
In Do-More you would just use the PONOFF instruction to make a push-on/push-off toggle from a button/switch. In Productivity you would use a TOGGLE instruction. Then just set bits as retentive memory in either platform. So dont think that really helps you with your Milwaukee PLC.
To do it manually with set and reset instructions, I would make a rung with the pushbutton as an edge triggered start to the rung, then branch off to "button is on" tag an NO on one branch and NC on the other branch. Then use a corresponding set or reset instruction to turn it on or off based on which branch of the rung goes true based on its status at the initial push of the button. Then do whatever is necessary to copy that bit status that is being set or reset into retentive memory space
On power up, make a "first scan" rung that then has a "bit status = 1/true" for the retentive version of the bit, then set the original bit you were toggling with the button to be on.
Yeah, I've used both of those instructions with great success. Maybe it was a Click where someone used a Set/Reset; memory is shot.
For all the money they charge for their hardware/software, you'd think they'd come up with their own version of the same instruction over there are A-B/Rockwell.
Then again, maybe they call it something else? I just had to go through a coding hoop just so I'd know whether the processor was in RUN. I had to code a GSV to an MEQ to an output Bool, and they think this is better?
I'll just email my local A-B rep's PLC guy; he may have an answer.
Thank you.
Do-more has a PONOFF box that does that. I just tested retentive behavior on the Sim and it worked ( => it should work with real Do-more PLC hardware ). I did it with a C bit - Y (physical output bits) are NOT retentive by design in Do-more PLCs.
I know this doesn't answer your question (just pointing it out for others). I'm guessing someone just did it in Do-more using basic Ladder because they did not know PONOFF already existed - and that's what you remember and are looking for?
Possibly, my memory is not what it once was.
I thought their memory defaulted to retentive? People argue about the utility of OTL/OTU but one common usage agreed upon is for bits that need to survive a power cycle and that is made possible by the retentive nature of those.
Unless you're in the Fisher Price one they have, no experience there.
I think INT, SINT, DINT, etc. default to retentive but not sure about BOOL. Is the Micro800 the Fisher Price PLC? LOL! Gotta say I'm no fan of CCWB.
I was going to post an answer, but when you mentioned the Fisher Price unit ... shudder ... I had to work on one once to add a new Modbus device to an existing serial radio network ... never again.
Our Rockwell rep occasionally mentions them, and I cut him off, "Nope, sorry, Click runs circles around it and the software is free and isn't complete trash like CCW. We'll never use them."
There are a few folks on the PLCTalk forum who tolerate them well enough to know the answer if you post your question there.
I'm actually programming a CompactLogix in Studio 5000 V37. I'm working with a customer who's more comfortable with A-B and their distributor is a mile from their plant. I'm replacing a SLC504 72 I/O PLC that is also sending signals to 3 Indramat servos to an all A-B PLC/servo setup. The toggle logic is an adder - that I've used with great success in Productivity and DMD - for future use.
I did on one occasion use a Micro800; Not a fan.