CP343-2 not detecting ASi nodes

[beethoven_ii]

I've been called to a site to assist with an ASi fault. The line has been down for a couple of weeks following a failure of the ASi power supply which I'm told blew up. Since then the plc (S7-314) has been replaced and the ASi master module which is a CP343-2 (6GK7 343-2AH00-0XA0). I'm online to the plc and it's perfectly happy, as is the ASi master module but no nodes are being detected and all the nodes in the field have solid red fault lights on. I've tried disconnecting the cabling to the field devices and connecting just one node onto a short piece of ASi cable and the master module doesn't detect it. The power light is on and the module is scanning through the network with the 10, 20 & B lights going on and off but nothing is being picked up. Has anyone had a similar experience and any ideas on what might be the cause of this?

 

[parky]

Never worked on the siemens ASI system (well never configured one , Have a lot of experience on Mitsubishi & IFM ASI nodes, I wouldn't be surprised if there are some damaged ASI nodes, As I say not siemens but on the Mitsi ones when you put it into detect mode it cycles through the ASI nodes, it skips ones that are not detected, if you press the store key(s) then it only stores the ones it finds & goes into run, however, things don't work because some nodes are missing, If you have an ASI programmer it would be best to check all those nodes, I hope you have a list of all the addresses or your in the deep end, I have had where someone replaced two ASI sensors but got the Addressing mixed up & another where there were a couple of faulty nodes the engineer replaced one but did not programm it, the ASI card automatically set it to the first one but it was the wrong address (Mitsubishi can automatically set an ASI address but only if one is missing & only if it reports it as being set to 0 address). not sure if this helps. Our system that contained something like a thousand ASI nodes on 10 or so ASI cards was well documented i.e. all sensors or valves had a tag with the details as well as a very large spreadsheet prinfout of all the addresses.

 

[beethoven_ii]

The system I'm looking at only has about 10 nodes on it and the plc program is quite small. They only have raw code with no comments but I can see the code that reads and writes to the master module and I know it is working as it overwrites any data I try to put in the db it's moving the data to. I have disconnected everything from the master module and attached a short piece of ASi cable with an I-O module on it with address 25 and put the master into configuration mode, but it scans the network and doesn't identify any addresses with the led's on the front of the module. The field nodes when connected have solid red fault lights which means no ASi communications and when I connect my single device with the field devices disconnected the single device fault light flashes red.

 

[parky]

As I said, I do not know the Siemens ASI cards, so as you only have what appears to be an upload of the PLC I wonder if there is some sort of configuration you need to do on the card itself, not beyond the realms of possibility.
When an upload was taken did this include any prameter settings of the PLC & any other cards ?.

Have you read this manual,

https://cache.industry.siemens.com/...8/v1/CP_343-2_Manual_2008-08_X-2010-08_en.pdf

 

[beethoven_ii]

I've taken advice from another automation engineer I know and also found a thread on here which points to the power supply being the issue. The site haven't fitted an ASi power supply to. replace the failed unit, just a normal 24v one. I said to them that it should be 30v and so we swapped it for one they had with an adjustment screw and got the voltage up to 29.5v. From what my friend told me it needs to be a dedicated ASi supply. In the other thread I read in here people have advised the same because the ASi power supply forwards the comms signals and a normal power supply doesn't. We'll see what happens when they try a different power supply.

 

[parky]

Yes that's correct, I do remember now that one of our engineers tried it & ended up having to fit the correct PSU, also, the ASI ones we used were IFM & if you get a short they just shut down without damage, also probably not in your case but the max length of ASI cable is < 100m regardless whether it is star or radial, total length of cable we had two loops that we had dropouts on, when we measured them they were 94m 97m, I put repeaters in at about 80m & 2 extra PSU's, cured the problem.
I don't think it forwards the coms as such as the PSU is normally just connected across the two terminals via seperate connectors on the card, at least on the ones we had, I think it just might be some filters in the PSU that stops the smoothing circuitry from attenuating the coms.

 

[beethoven_ii]

Just a quick update for anyone who comes across this thread. It was a power supply problem. Customer’s standard 24v power supply has now been swapped for an ASi power supply and everything is back up and running.