Any one here familiar w/sequential operations - ladder logic controls , PLC S?

APPLICATION
Currently there are 2 entrance lanes into a facility and one exit
Seperated by a guard shack

The two lanes have barrier arms
card readers , they converge into one lane after access is granted and have a "bottleneck " potential.

The customer would like to have a sequential operation ,to diminish
possibility of accidents .

So when cards are presented at both Lanes at same time or close to ,only one arms goes up at time. It's important that the other input
Be held in memory so as to not have to present card a 2nd time.
Further there are occasions when
(carpool 2-4 people) multiple cards are presented
At one time one side.

The current install has new chamberlain mega towers installed , and they claim to have a sequential relay - it does work ,intermittently however after 1-1000 cycles it randomly locks up both sides.
The current set up utilizes only one loop per barrier arm - a presence loop ,and that acts as a close input.

Independently these units work 100% ok ,only the addition of factory relays caused issues.


I m working w/ factory ( useless ) factory rep ( more useless) and my customer is ready to pull plug .
Anyone here familiar with a sequential control setup ?

http://www.liftmaster.com/consumerweb/pdfdocs/0160162.pdf

see page 17
for those of you that have followed so far

Thanks for any insight

Is you are asking about PLC's in general, yeah, there are a few controls guys here, but unless you have the ladder that is programmed into that controller board (or have some way to look at it/post it online) then we won't be able to help much.

given the info I have - all I can suggest is that you re-check your wiring, verify every input (is anything chattering ?). Check power going in - is it within spec and grounded well ? any large switching/electrical noisemakers nearby ?
Lastly, tell the manuf. rep to get you a new board, as the firmware on the existing board is not operating consistently.

(there is a troubleshootnig flowchart on pg13 - that should be enough to satisfy the manuf. as to thier junky stuff =)

-John

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What or whom insures all passengers present an acceptable ID at a gate?

Card reader.

the access control system ( lenel?) verify s cards - my barrier arms recieve
a momentary closure from a dry contact .

How can a card reader count passengers in a car?

What do you mean by "locks up both sides?" Are both arms DOWN and won't move, or literally locked UP?

Do you know the status of D1-D8 in each controller at that time?

Are both controllers signaling for OPEN but neither has won the contest?

Has one car raised the arm and left the loop, but the loop input did not clear, meaning a loop problem?

Cool puzzle, man.

Chaz - the card readers can only read what put in front of them - prox type
and the driver presents all his passengers cards

Jim- As we witnessed this week Diagnostic lights on when units locked Up
D1 D3 D5 D24 When reset No D1 No D24
Dont think its a loop issue - they work fine , they act as a close input
- customer preference

I would prefer to time the close and have the loop act as a safety
( my thinking is that it just creates another input into the board on the
close input- along with all the open inputs / card presence)

- the units "lock-up'' in the down position - never cycle


I just am not familiar enough with set ups - but its similar to a "Sally port " type configuration -where one is open the other is holding close - either or

called Viking Access manufacturer yesterday , they are looking into a set up w/ there barrier arms . Great Company - very responsive , nice boards ,etc

(not that I know anything about this)

But would it help to separate the arms out and direct carpools only to one side, which also is the only arm that delays?

That way, one arm would work normally, read a card, and open, while the second arm would wait only until that primary arm is down to open.

How does this thing handle multiple cards? wouldn't it open with one card? Do you have to press a button saying carpool?

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So, "Locked UP
D1 "Relay" (relay activated?)
D3 "Close limit sensor" (gate down)
D5 "Motor brake on" (gate is not going to open yet...)
D24 "Shadow" (input from shadow loop

"Reset"
D1 "Relay" (relay activated?)
D24 "Shadow" (input from shadow loop
Gate may (or may not be) down and brake is OFF. This sounds like the arm has been released and on its way up...

Why would the "Shadow" input be active whether Locked Up or Reset? Isn't this supposed to clear when the 'other' unit cycles the "Relay" ? I don't know anything about these operators, but this is what I would wonder...

Good luck.