Problem in PLC system

[John Morris]

Can you move between other screens on the HMI

Guess I should ask first, does the HMI have more than one screen,

and if so can you move from screen to screen

 

[redbarron55]

To help troubleshooting you might want to program a timer or something PLC in the to give numbers to read in the WW page so you can see it updating.
What is the communications link between the PLC and HMI?
I would look there and at the DAS in wonderware for the problem.

 

[Osama Badr]

What is the communications link between the PLC and HMI?

RS232 cable
RS-232C connected to copmuter case
RS-422 connected to hitachi CPU 22-02HC socket

 

[brendan.buchan]

Was the machine off for an extended period of time when this happened? When was the PLC battery last changed?

It could have lost its program. It's odd that the run light is still on and there is no fault light but I'm not familiar with these Hitachi PLC's and how they will behave in this situation.

 

[redbarron55]

I think you have found your "PLC" problem.
The HMI is losing communications with the PLC probably due to the RS232 (two Wire) on one end and RS422 (4 Wire) on the other.
It is one or the other from one end to the other.
You must have the proper cable and termination resistors in the line.
Google RS232 and 422 to see the differences.
If you have the choice then RS422 would be better.
You may need a converter for the PC and install the 4 wire RS422.

 

[Osama Badr]

I think you have found your "PLC" problem.
The HMI is losing communications with the PLC probably due to the RS232 (two Wire) on one end and RS422 (4 Wire) on the other.
It is one or the other from one end to the other.
You must have the proper cable and termination resistors in the line.
Google RS232 and 422 to see the differences.
If you have the choice then RS422 would be better.
You may need a converter for the PC and install the 4 wire RS422.

it's special cable
the cable have two ends
1-RS232C (female) connected to computer
2-RS422 (male) connected to CPU

i exchanged it before but the problem still .

 

[roxtech]

Hi, I think you have no communication between PC and PLC. What is type of communication you have? Now your PLC is in run mode, no error. but you can not start or stop any motor from PC.

 

[Osama Badr]

Hi, I think you have no communication between PC and PLC. What is type of communication you have? Now your PLC is in run mode, no error. but you can not start or stop any motor from PC.

it's special cable
the cable have two ends
1-RS232C (female) connected to computer
2-RS422 (male) connected to CPU

i exchanged it before but the problem still .

 

[redbarron55]

Check the comms and the baud rates etc.
Also program a counter with reset to generate changing numbers so you can look at it with your HMI.
If the numbers are changing you are connected, if not you are not.
You need to check the setup of your wiring and the cabling.
Electrical noise could interfere with the signals and check for this as well.
I wonder if the cable is proper for the communications.
Look up the wiring for the signals and make your own cable.
also you need to make certain that you have the proper terminating resistors on each end for the system to work.
google RS232 and RS422 to understand the difference nd how they work.

Here is a link to a site with an explanation:

http://www.rs-485.com/comspec.html

I believe if you get your communications working you will be on your way.

 

[Osama Badr]

Check the comms and the baud rates etc.
Also program a counter with reset to generate changing numbers so you can look at it with your HMI.
If the numbers are changing you are connected, if not you are not.
You need to check the setup of your wiring and the cabling.
Electrical noise could interfere with the signals and check for this as well.
I wonder if the cable is proper for the communications.
Look up the wiring for the signals and make your own cable.
also you need to make certain that you have the proper terminating resistors on each end for the system to work.
google RS232 and RS422 to understand the difference nd how they work.

Here is a link to a site with an explanation:

http://www.rs-485.com/comspec.html

I believe if you get your communications working you will be on your way.

thanks "redbarron55"
connection cable is exchanged with a new one and it is OK
baud rate and other values are Correct

but if all above are correct
how caN I KNOW THE MEMORY OF CPU?
the correct value =.....?
if i found it as 0 value is that have indication for action?

 

[roxtech]

Hi,
CPU has not RS422 communication. Is there any modem between them? Do you have manual for CPU. Do you have programming software HILDR for CPU? DO you try with stop and run again by key switch on PLC CPU? Do you have alarm or indication for status of any motor on HMI/PC? IF you have such alarm or indication just try to force trip any motor any check its status for your communication ok or not.