SLC 5/04 - Added 1746-BAS faults CPU

Hi, I have an SLC 5/04 which has been working fine. Just added a 1746-BAS module to the rack and have got real problems.

The BASIC module seems to be working OK "stand-alone" - I can enter a program and have it run and it seems to be OK. Just "Hello World" type stuff though.

However, it seems to break the processor - the processor faults and even worse, seems to get corrupted. Power down/reset don't work, I have to remove the battery and short the capacitor to recover the situation.

On the odd occasion, I have had the BAS module working with the processor in RUN, but when I power off/on, it always fails on restart.

Is there some essential ladder that I am missing to make the processsor aware of the BAS module and co-exist with it ? All I have done so far is to configure it as an I/O module in Slot 2. Is anything else required ?

(I know the BAS module is quite old, but I am not going to replace it with a Prosoft module).

I am starting to think that the ("second user") BAS module is faulty ?

Any help would be greatly appreciated,
Regards
Dave

Have you got the correct module installed in the processors IO config ?

504bloke said:

Have you got the correct module installed in the processors IO config ?

Click to expand...

Hi Dave,

thanks for the reply. The Module is marked as an SLC 500 BASIC MODULE with part number 1746-BAS SER C FRN 6. RSLogix 500 7.1 has options for :-

1746-BAS-5/01 Basic Module 500-5/01, and
1746-BAS-5/02 Basic Module - M0/M1 Capable

I think it must be the former, so that's the one that I have tried most times, although I have tried both options - pretty much with the same results though,

Regards
Dave

Did you add the card to the I/O list while offline and then download the new configuration to the processor?

Hope this helps.

Bob O said:

Did you add the card to the I/O list while offline and then download the new configuration to the processor?

Hope this helps.

Click to expand...

Hi Bob,

thanks for the message - yes, that's what I did, the penny may have just dropped though - off to reconfigure the system to try something....

I may have misread the meaning of the descriptions of the I/O modules.

As I said earlier, in RS-Logix, there are module descriptions for :-

1746-BAS-5/01 Basic Module 500-5/01
and
1746-BAS-5/02 Basic Module - M0/M1 Capable

I read this as meaning two different types of 1746-BAS module - duh! I think that it relates to the CPU in the rack, i.e, 5/02 and above supports M file transfers and the 5/01 doesn't.

I'll write back with an update soon,
Regards
Dave

Aaaargghhh ! OK, it was a good theory, but still no joy.

OK, here's what I'm doing - starting from where the module has screwed the whole thing.....

The PLC is in fault, with no comms between the processor through the 5/04 RS-232 port, and dead to the world. No amount of powering off/on does anything.

Remove the BAS module, and power on - no change.

Remove processor, disconnect battery and short capacitor to remove all configuration and user program.

Reconfigure offline to remove BAS module, download to PLC and the system restarts and works fine.

OK - try it again.....

Add BAS module offline and download.

Install BAS module (port configuration tried in various modes, i.e., PRT1 as program port or ASCII).

Power on PLC.

The first time only, it runs, at the next power off it fails and back to the state described above - i.e., failed/dead.

Any ideas folks ?
Regards
Dave

Is there an EPROM installed and if so are you saving to the EPROM?

Is your rack Power Supply big enough for the added module?

Hi Folks,

thanks for the replies - things are worse (or in one way better) than I thought !

It's looking like the problem is not with the BAS module now - although I don't know whether installing it csused the problem or not.

It seems that it may be the CPU, PSU or backplane that has the problem. I thought that the problem had just started when I installed the BAS module, but I can't be sure now.

With no BAS installed, the rack sometimes does not start up correctly after power loss. I might have to start a new thread !

The BAS module seems to be working now anyway, so thanks for the help.

Regards
Dave

Have you backed up "new" program with BAS module in the configuration to the PLC EPROM. The PLC may be configured to read from the EPROM on power up and run that program, if the BAS module is not in the EPROM saved configuration then the PLC will definately fault.

To Store an EEPROM
1 Go online with the SLC controller that has the EEPROM you want to store to.
2 Select Comms > EEPROM > Store to EEPROM.
3 The SLC controller burns the EEPROM.
(from RSLogix 500 help file)

Hi, thanks for the tip.

I don't think that the CPU has an EPROM fitted, I get errors if I try to read or write to an EPROM from RSLogix. The manual describes the EPROM as optional, so I'm assuming that there's not one in my SLC 5/04

Regards
Dave

stevendt said:

Hi, thanks for the tip.

I don't think that the CPU has an EPROM fitted, I get errors if I try to read or write to an EPROM from RSLogix. The manual describes the EPROM as optional, so I'm assuming that there's not one in my SLC 5/04

Regards
Dave

Click to expand...

The EEProm could be write protected so it may give you errors.

In Logix in the left hand pane (presume you have a copy of the program) click on Processor Status, scroll across until you get a MemModule tab and see if any of the bits are set there, this will give an idea if a mem module is fitted.

Or the best way is to have a look, power down, unplug the PLC and have a look to see if there is an eeprom fitted (It plugs in next to the Battery) like a 1747-M11 etc

504bloke said:

The EEProm could be write protected so it may give you errors.

In Logix in the left hand pane (presume you have a copy of the program) click on Processor Status, scroll across until you get a MemModule tab and see if any of the bits are set there, this will give an idea if a mem module is fitted.

Or the best way is to have a look, power down, unplug the PLC and have a look to see if there is an eeprom fitted (It plugs in next to the Battery) like a 1747-M11 etc

Click to expand...

Hi there,

thanks - I had the CPU out earlier - there is a socket close to the battery which is empty - I'd guessed that a memory module went there, but wasn't sure if that was where the EPROM went.

Just looked on the page you described in RSLogix - all the bits are clear, so I guess that confirms no EPROM module is fitted,

Regards
Dave

I had a similar problem with a micrologix 1200 and it ended up being a faulty analogue combo module. one day it decided to quit and I could cycle the power and it might work and it might not, but it never gave any trouble after the plc entered run mode. I replaced the module and haven't had a problem since. If my memory serves me correctly, when I would try to view the installed modules through rs-logix I could not see anything past the analog module and that is how I was able to pinpoint the problem module. The mx1200 daisy chains all of its add on modules instead of using a backplane so it may be a little different to diagnose,but you could try to view all installed modules next time it goes down and see if they all show up. Hope this helps, Jason

Thanks Jason,

at one point I thought that it might have been a faulty 1746-OW16, I had taken the rack down to the bare bones - no I/O modules and was adding them back in turn. One 2-3 occasions, I could start it without that one module in, and not start it when it was fitted. I was quite happy (well, almost) that it was just a faulty I/O module, but the next few times, it failed on other modules too.

Unfortunately, when the rack won't start, I can't get any comms to the CPU to see the processor status so it's hard to see what the fault is.

I'm reading up to see how (if) I can get it to ignore errors to at least let the comms start,

Regards
Dave