simtic op7 failure

frequently the op7 simatic panel getting failed
it measures the temperatre & other parmaters.
all the temperature value are showing -250
what is the reason
it can be solved or to replace the panel
please send solutions

How do you know that it is the OP7 that has failed ?
It could be the analog inputs in the PLC, or maybe a common power supply to the temperature transmitters.
Many more details please !

op 7 failure

we have two identical view panel with plc CPU ,INPUT MODULE & temperature transmitter.
we removed this error view panel 7 checked in the other.
the same result.
hence we concluded that the view panel is problem.

it is used in the absorption chiller.
it has to show the temperature of coolin water & chilled water.

but all the temperature readings are - 250 indicating.
i feel that there is no communication between the view panel & cpu.
the communication cable is good.

kindly guide.

Firstly i would find the Tag address of the value in the Protool project then find it in your S7 Program,view online through simatic Manager and establish what value is the CPU reading from your Card. If the Value is ok in your S7 project and not at the OP7 then i'd check the programming which displays this value - Incase a recent change in the code has resulted in the wrong value being written. I may be wrong but i doubt the OP7 is to blame(famous last words!)

Hope this helps

Steve

we removed this error view panel 7 checked in the other.
the same result.
hence we concluded that the view panel is problem.

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Not sure how to interpret these two sentences.
Did you exchange the OP7, and the problem stayed ?
If so, it looks like the problem is NOT with the OP7.

we have two op7 view panel with the same programs 7 functions.

as we identified the problem with one , we removed the erroe panel & fix it in the other system & vice vesa. still the same problem persists.

i mean we done it to cross check is there any fault in cpu & input modules.
Thus we got assured the problem is in op7

kindly help

we removed the erroe panel

Click to expand...

You removed the panel that displayed the "-250" values, or ... ?

& fix it in the other system

Click to expand...

You "fixed" the problem in the OTHER OP7 panel, or ... ?

i mean we done it to cross check

Click to expand...

You mean to say that you have exchanged the OP7's and the problem stayed, and it stayed at the same system (it didnt follow the OP7) ?
If so, check the analog signals. The "-250" seems to indicate that it is 4-20mA signals and that the signal is currently 0 mA, or is interpreted as 0 mA.
You can try to exchange analog input modules between the two systems.
If this doesnt resolve the problem, you may have to go online like stevo suggests.

stevo said:

Firstly i would find the Tag address of the value in the Protool project then find it in your S7 Program,view online through simatic Manager and establish what value is the CPU reading from your Card. If the Value is ok in your S7 project and not at the OP7 then i'd check the programming which displays this value - Incase a recent change in the code has resulted in the wrong value being written. I may be wrong but i doubt the OP7 is to blame(famous last words!)

Hope this helps

Steve

Click to expand...

Dear Mr. stevo,
i hope you understand my problem of op7. there is no problem in CPU or analog input modules. we confirmed that this problem is in view panel.
the same problem happend a year back & we replaced the complete view panel.
but i hope replacing is not a solution. this problem can be solved .
hence guide me to solve the problem

Hi navashab,
Ok if you are happy that all is well on the PLC Side,What i would look at next is the following.

1. Make a backup of the OP Program using Prosave if you dont have a protool project.
2. Erase the configuration within the OP
3. Reload your Program - Preferably from your Protool File

If this doesnt work i would define a new Tag and change your S7 programming address to this, Load it up and see what happens! even make a new screen if you need to.

The OP System Error messages are quite comprehensive,it seems strange to me that if the unit has failed that it doesnt report it.

One last thing are you sure that you dont have any overlapping addresses in the Code?

Regards

Steve.