TI 505 PLC weird Behavior..

[atifplus]

I was writing a value on V1000 and it was changing the state of X3 which is a 3 bit on the input module .. :|

is there any linking with the memory inside PLC that i have to reconfigure b4 i download the logic ...


Thanks in adv.

 

[Ken M]

Hi there


In 505-series there is no intrinsic link between any V-memory and the image register (Xs, Ys, WXs, WYs). The only connection that will exist is through the program or the process or both.

You can not write to an X input by any means from within the program logic. If a change of state in X3 appears to coincide with a change of value in V1000, then that's just what it is: coincidence. To find if there is a causal connection between these events requires deeper invesigation.

- What happens to the value in V1000?
- Does the program use it, for example, to control an output (either digital or analog)? The connection internally could be quite indirect so you need follow through any paths thoroughly.
- What external device is X3 wired to?
- What physical condition makes this device alter state?
- Does the PLC have any influence over this physical condition?
- Is V1000 involved in the decision-making to determine this influence?

The answers to all these will be with you somewhere.
Good luck hunting.

Regards

Ken

 

[Ken Moore]

Can you post you logic?

 

[atifplus]

Well the logic dont have a lot of things in it all. Just 3 networks in total.
Out of those 2 are to configure the Ethernet Module.

Then last one is
input

X3 -------- Y1
|--Y2
and so on till Y7.


Even if i load a blank logic (means just one network of internal coils) in the PLC some of the output points are at "ON" state and linked to inputs. Means without defining in the logic the X1 turning on Y1 somehow. and so as the rest like X2 -Y2 and X3-Y3 .... ( I have a panel with the pushbuttons mapped to X1-X7 and Bulbs Connected to Y1-Y4.



Also, When i wrote a ladder in which X3 -- Y2 and i force X3 or hook up a push button to X3 and push it. it shows the Y2 is turning on in the logic but the bulb donest turn on however if i force the Y2 in the logic the bulb turns on. ( the Y2 was turning red both the cases) ..

I just dont understand why is that.. Also, Is there any other block we need to put in between input to output connected though wire or i can have just the wire( which i am doing right now)

I will post the logic.
The PLC i am using is 555-1101 and output module is 505-4816 ...



Thanks for all the help

 

[atifplus]

Hi Ken,

I am not sure what deeper investigation are u talking about I mean i dont have a lot in the logic at all just 3 networks. I tried a lot of times with just small logic programs like hardly 5 networks to test but seems like i can't turn on output physically unless i force that point. (force as in right clickin and going "force on")

I wrote a really simple logic to test the PLC but no conviencing results.

however what i have in my last logic is ..

- What happens to the value in V1000?
though IFIX i was writing value of 1 at V1000 and I can see in data window that it is reciving the value 1

- Does the program use it, for example, to control an output (either digital or analog)? The connection internally could be quite indirect so you need follow through any paths thoroughly.

The only place i am using that V1000 value is to compare with 1 and if it is 1 then it turns on the Y3


- What external device is X3 wired to?

A push button in series with power source



- What physical condition makes this device alter state?

Y3 a bulb aaa pushing X3 (push button) or Clickin the softtag which sends 1 to V1000. Also i have no connectino between X3 and Y3 in my logic. Also When i do the force on Y3 it shows Force sign on the X3 too .. seems like they are link but not in the logic somewhere else .. Oh my logic have lots of lots of NOP (No operation) hope that is not causing the problem.

- Does the PLC have any influence over this physical condition?
If i force the Output points (means by right clicking and the go FORCE On then only the output gets the signal other than that no matter what logic is doing (even though it shows on 505 that Output (Y = bulbs) getting value of 1 but they dont lit the bulb


- Is V1000 involved in the decision-making to determine this influence?
again not a hold lot of logic there hardly 3-5 networks.


I tried writing lots of different logic to figure out if there is something i am doing wrong but i just have no idea why the PLC is behaving like this.

and why the inputs are automatically mapped to the corresponding outputs without defining in the logic.. is it something to do withthe config of PLC processor module ?? ( I followed the manual for the dipswitch setting for that)

 

[Ken Moore]

I think we have found your problem.

You said you had X1-7 and Y1-4, in the 505 plcs, the X's and Y's occupy the same block of memory. There isn't X memory and Y memory, there is X/Y memory.

What does this mean? It means X1 and Y1 occupy the same physical memory location, that's why you cannot have an X1 and a Y1. When X1 is true, a 1 is placed in the image table, at the end of the scan, the PLC see's a 1, and energizes Y1.

You will have to reconfigure your I/O, start your X's at 1 and your Y's at 101 or something else not assigned to the input card, your problem should go away.

 

[atifplus]

Hello

Thanks a lot for such an important info Ken. I thought the output and input are seperate mem. in PLC

I will reconfigure it and try it

Thank you so much for this info


Atif