MCE PHC 1000 control, submersible hydro, 3 stop.
Car on automatic, you put in a call, it comes to the floor, the doors open, then the dwell time expires, then the doors begin to close maybe an inch or so, then they snap back open. Process keeps repeating. I think it generates a fault after a bit, but I can't remember that detail now, but it's not germane, as it's unrelated to the cause.
All re-open inputs are clear, no i/r edge or s/e input, no DOB input, no car or hall call input. All contacts in door operator working correctly, and clean.
DOI, (Door Open Intent) software flag is low, during symptom.
As I'm writting this, I'm thinking "Someone has had this problem before, and will solve it immediately".
i thought id try having never seen this equipment!!
This has been up a couple of days, with no takers, so I'll spill it. But first, you should know that on Motion Control Engineering controllers, there is a software flag, know as Door Open Intent. (aka DOI) Basically, it just tells you if the program is calling for the doors to be open. For example, if some demand was established at that floor, or if any re-open device was actuated, or if there was a fault of some kind. None of those were the case.
Since DOI was not active, the controller program was not asking for the doors to be open, yet they would spring back open, immediately after beginning to close. No input device was telling the control to open the doors. Another way to say it, the doors were re-opening, on command from the controller, for a reason other than the control programming telling them to do so. If I say any more, I'll spill the beans..!
Before I tell you what it was, do you want to take a stab at it? It might harder for you, since you haven't seen how the equipment is built. No shame to pass on this one... 8^)
This problem could just as easily occur with c/o.
Nope!
Isn't this fun? 8^)
One time, I had a similar issue, where the bus voltage started at the operator, went back to the control through a long traveler for switching, (do, dc, nudg), and then back out through the traveler. By the time it got back to the operator, there wasn't enough voltage for the signals to be recognized. I installed "pull up" resistors, right on the operator, from the bus source, to each input. It just needed a few extra volts on the inputs, aiding the signal coming back from the controller, for the signal to be recognized. When the control would switch the input off, there was only a few volts idle on the inputs, not high enough to reach the switching threshold.
MCE, on their PHC 1000, used triacs to complete the path to ground, and this is how their "outputs" work.
The Door Close Front (DCF) triac brings in the Door Open Relay. If this triac is shorted, the doors will open normally, but then when the dwell timer expires, and the Door Close Relay comes in, the doors begin to close noramlly, but then as soon as the Door Open Limit changes states, the shorted DCF triac then brings in the Door Open Relay. Then the doors snap back open, they time out again, then try to close, and the process keeps repeating. The effect is that the doors just keep whacking off near full open. Changing the shorted DCF triac makes the problem go away.
Hope this was at least slightly intrigiung!
damn.
Yes, you're right, I made a bad typo. I was trying to refer to the DOF triac, like you say.
I'll have to get back to you tomorrow on the sequence stuff. Wifey is calling me to bed. She must be tired...
I've only got a traction print here with me, hope it's about the same...
"seems to me that DC, and DO will both be picked at the same time as soon as the door open limit makes and puts the 2 side of the line on terminal 36. both relays would have to be picked, since the cpu is outputting DCF to close the doors, then the door open limit makes and since DOF is shorted, DO would pick up, but, the cpu would not have any way of knowing that D0 relay was also picked, it can not tell that the DOF triac is shorted"
Hmm, lets' see....DOF triac is shorted, so any time the Door Open Limit is made, DO relay picks...ok...And on this print, DOX is in parallel with DOF, so you get that one in, too..
DOX n/c is in series with the DC relay coil, so when the doors start to close, as soon as the door open limit closes, DOF and DOX pick due to triac DOF being shorted, and DOX n/c opens, dropping the DC relay. So DC and DO aren't in at the same time
Do I get a star on my forehead? 😊