1747 ASB and 1747-SN coms problems

[sparkie]

We had a storm last night, and the smoke got let out of some of our PLC equipment. I'm troubleshooting a link between a 1747-SN and a 1747-ASB.

Both of their dip switches for the baud rates are set the same (0 1).

When powering up, the 1747 ASB gives the following messages:

Red Fault LED on with PUP
Red Fault LED flashing with bnc

The 1747 SN powers up
Fault LED turns on
Coms LED turns green
Coms LED turns orange
Both LEDs turn off.

I'm a bit stumped here. I didn't do the replacements, but the tech told me that he set the dip switches as they were before. I verified this the best I could, but it seems like we have a communication issue, and I'm leaning towards the 1747-ASB.

Can the cards on the remote rack be placed in any position and still work fine given that there is only one IO scanner? We have several spots in the rack that are unused.

 

[Geospark]

There is more than the baud rate dip switches that must be set correctly. Look here to double check your configuration...

23925 - Quick Start Remote I/O
Access Level: TechConnect

The remote modules can be placed anywhere in the rack, but the ASB must reside in the first slot of the remote rack.

Regards,
George

 

[sparkie]

Yessir. I've went through dip switches last night. We managed to get the main system up and running, but we are still having issues with this remote rack (it mainly just controls some valving and flow meters on a discharge system).

We had a tech down here helping, but I have changed out pretty much every part in the system and I keep getting errors. Even with all the cards removed from the rack, I get a "no com" error on the 1747-ASB and a flashing red light on the scanner module.

I am working on this part of the problem right now, but so far we had 3 bad cards, a bad PSU and 2 bad racks.

I am thinking we have a configuration issue on the adapter module (yes, I also did a resistance test on the wire and checked it to ground).

 

[Geospark]

Hmm, you appear to have checked all the likely causes for a 1747-ASB "noc" error?...

14999 - THE 1747-ASB STATUS DISPLAYING A " noc " CODE
Access Level: TechConnect

I'm inclined to think it may be at the SN module's end, but obviously I cannot be sure while sitting here.

If possible to carry out, have you tried the SN in a different slot, if available?

...I have changed out pretty much every part in the system ...so far we had 3 bad cards, a bad PSU and 2 bad racks...

I'm wondering if that list is going to grow?

Have you already done so, or considered changing out the SLC rack where the SN module resides?

Have you changed the remote rack?

Are they the "2 bad racks" you are referring to above?

Regards,
George

 

[sparkie]

This was a nightmarish ordeal for me to go through within my first three months in the field. To compound matters, though their intentions were good, I had two other techs there changing out cards before I got there and had no clue where they had the cards and also had no way other than verify on a switch-by-switch basis the position of the DIP switches on the 1746-ASN.

My hypothesis is that the root cause of this is that lighting struck some of our above ground piping and that this surge traveled up through the analog connections to the rest of the system.

Ultimately, I still had 4 more bad cards. I ended up (verifying of course as I went) having to change

1747-SN
1747-ASN
2 x 10 slot SLC racks
1 x 1746-P4 Power supply
2 x 120V Inputs
1 x 1756-OW16 Relay out card
2 x 1746-NI4
1 x 1746-NOI4

1 x Gas flow meter
1 x Liquid flow meter
1 x Transmitter for liquid flow meter.

The noc problem ended up being at the 1747-SN card. As far as the parity issue, changing out the remaining three cards in the remote rack resolved this issue, and any time I tried one of the old cards the parity error would return.

I am pretty proud of myself on this one, I resolved the situation with minimal help, but man it was a brain and nerve racking ordeal.

 

[Geospark]

Well done you!

shock:Cough* "Surge Protection" Cough*)


http://literature.rockwellautomation.com/idc/groups/literature/documents/br/4983-br001_-en-p.pdf

Specifically the BULLETIN 4983-DH Heavy Duty AC Surge Protective Device, or some other equivalent.

Might be worth looking into after your "in-at-the-deep-end" and I'm sure costly ordeal?

p.s. that list sure did grow alright!

Regards,
George

 

[sparkie]

Well, I believe the surge came in via our flow meters and a strike to an above ground pipe rather than through the power system. The surge went through the data cable going back to the 1747-SN and got the inside rack, but our outside analog inputs took the brunt of the blast. I'll look into the surge protector, but I'm thinking perhaps a lightning rod system may be a good way to go.