Automation Direct DL05 and DirectSoft

geniusintraining

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Jun 2005
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Hello everyone, I have a customer that needs some help and I dont really understand the question so im posting it here, I think he is over thinking the problems

I’m stuck because I do not fully understand how the ON/OFF for outputs really work.

For example, I wrote a rudimentary program to mimic the operation of a traffic light that controls a North/South and East/West intersection. My process is simple:


Start:

Green_North (Y0) and Red_East (Y5) = ON

After TMR A reaches 100,

Amber_North (Y1) and Red_East (Y5) = ON - - Green_North (Y0) = OFF

When TMR A is between 100 and 200

Red_North (Y2) and Green_East (Y3) are ON - - Amber_North (Y1) and Red_East (Y5) are OFF

And so-on until the cycle repeats itself.

Obviously, I’m in the “Cycle 2” hell. The scan of the process is seeing lights turn on at the start of my ladder and then seeing them turn off later in the ladder so when the output actually starts, the initially set lights never come on.

How do I fix this condition? Would “Immediate” output instructions work or is there a better process?

I have asked him for the logix he has made to date and will post once he shows it to me
 
I'm on my phone so I can't look at it but anyone wants to help I'm attaching the logic he zipped up

Thank you
 
On the road this AM so I still cant help much, anyone look at the file? below is a email from him, he has also registered on PLCTalk but he can not post yet

Mark,

I am an electrical instructor. The class I have starting on Monday is a PLC class but my focus is “What to do when the customer calls the electrician.” I have a lot of programming experience from my days with IBM, but that is with full blown programming languages.

I’m trying to get my arms around programming so that I can effectively write code that will give the students the appearance of hardware failures so that they can go through the panelboards that we have set up and test for hard failures.

The last teacher left very suddenly, and the class fell smack dab into my lap.

Thanks for your help

I will try and look at the logic once I get back if no one else can
 
There seems to be a few things on quick glance. For example, what happens between 100 and 200 on the timer? I was going to put it into an 05 and simulate on an HMI and see what it does but haven't had the chance yet. This is the whole program. Rung 6 is end coil.

Capture.jpg
 
Yeah, you are using the programming logic that you would in the 'full blown' languages, where you list every possible input combination and define the outputs for those. ie.

Code:
if case1
  Output1=false
  Output2=true
Else if case2
  Output1=true
  Output2=false
Else
  Output1=false
  Output2=false

In ladder, a partially blown language, clarity is achieved by having all the logic for what turns on an output on the one rung. This is equivalent to writing this in full blown languages.
Code:
output1=case2 AND NOT case1
Output2=case1
You can see that both code snippets above give the same outcome.

In ladder we write this as

Code:
case2 case1 output1
-][----]/[----()

case1 output2
-][-----()

I hope you can extrapolate to your situation.
 
As I suspected, multiple coil usage. A common mistake by programmers new to PLC ladder logic, especially when the come to the field with experience programming in other languages.
In rung 2, instead of the coil addressed to Y0, use a coil addressed to C0.
In rung 3, instead of the coil addressed to Y0, use a coil addressed to C1.
Add an additional rung with a coil addressed to Y0, controlled by C0 OR C1.
Do something similar for Y1, Y2, etc.
 
Thank you for the replies

After looking at it... yes same output used several times as Steve pointed out

Bob, Yes I think this is as far as he has got... I see a long weekend for him :)

AustralIan, I think Don needs to pull out his Electrician hat and put the programmer one in the drawer

I have asked him to call me and I will update if I hear back

Thanks again
Mark
 
Is this a real world application or a lab for school?? Do they use DL Processors for Traffic Light control?
 
Classroom environment only

I all and thank you.

I'm finally allowed to post and respond. My goal here is to write this control program and get it operational. Once I have that completed, I am going to put hard electrical failures on the workstations and have the students trouble shoot the electrical failure, such as a relay with a blown coil so that it cannot pick.

However, until I get this program off and running I'm dead. I have until Monday of next week but that can slide as I have a lot of electrical items to cover before I hit this little beastie.

Pointers are gratefully accepted. Fingers pointing to documentation are also greatly appreciated. I don't mind doing the legwork especially since I will benefit from the knowledge.

Don
 
I'm having fun being a functional idiot :)

I rewrote the sample program using Control Relays as suggested earlier. I'm not at the school and won't be there until 18:00 tomorrow evening so I have no way to test what I just programmed.

If anyone could please unzip the file and run it against a DL05 or just read it and tell me what I am doing incorrectly and how I can fix it to make it work.

Don
 
Still not right

As was pointed out, AD doesn't work well with multiple coils. You still have your timer not consistent. I made a few quick changes and simulated it on an HMI and my changes worked ok. I wouldn't use it with real traffic but it stays along the way you were thinking, I think. (if you just load my program in, you'll need to change the C3 back to X3. It was just easier on the HMI)
 

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