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jeffersm

ControlNet problems on ControlLogix5000 system

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I am seeing intermittent problems with a process that is using ControlNet on a ControlLogix5000 system. The problem started happening about 1 month ago and there have been no program changes since 5 months ago. The system has the following: 1) 1756-L61 CPU 2) 1756-CNB/D Master ControlNet card 3) 1756-ENBT/A Ethernet Card (Only used for VFD, HMI and remote access) 4) 3 1794-ACN15/C FlexIO ControlNet interfaces for nodes 2, 3 and 4 on RG-6 bus We were seeing intermittent stopping of the process related to node 4. When the process stops, the technician can sometimes restart by stopping and starting the process. If that doesn't work, then he unpluggs the bus tap from node 4 and then it works. The following steps were taken to try to correct the problem: 1) replaced the FlexI/O on node 4 (just 1 high speed counter) 2) replace the 1794-ACN15/C on node 4 3) replaced the RG-6 cable (had measured high resistance from one of the cables to a tab and had another cable whose connector fell off during troubleshooting process. decided to change all as a preventive measure.) 4) replaced the 3 taps connected to the 1794-ACN15/C as corrosion was noticed on some. 5) replaced the bus/terminal block of the 1794-ACN15/C used on node 4 and the 75 ohm terminator I have checked the CPU fault history, but none were recorded. The technician mentioned that when the process stopped a watchdog timer fault message on HMI. My next step will be to get the exact wording of the fault to trace it back from the HMI to the related logic in the PLC. Last night the process stopped on all the nodes. I don't have the details yet of what happened or how it was corrected. Seems like the problem may be getting worse. Any recommendations on where to look to identify the problem? I have the RSNetworx for ControlNet installed on my computer, but I don't know if we have an interface to connect a PC for configuring ControlNet. If I swap out the 1756-CNB/D Master ControlNet card will I need to use RSNetworx for ControlNet to configure it? Was RSNetworx for ControlNet required when swapping out the 1794-ACN15/C node interface?

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Generally speaking, it is recommended to re-schedule the ControlNet network after every hardware replacement/modification. Sometimes you get lucky and the Keeper doesn't "raise hell", however, more recently manufactured products have different capabilities/requirements. The 1756-CNB bridge is the Keeper of your CNet network, hence it handles all the communications settings/functionality "enforcement". You will definitely HAVE TO reschedule the network. RSLogix 5000 could theoretically do it for you, however, we've found out that RSNetworx for ControlNet is still needed, especially when Keeper replacement/configuration is intended. For directly interfacing with your CNet network you will need the 1784-PCC Communications card installed on your laptop. However, since you already have an Ethernet/IP bridge installed within the Logix chassis, you could drill the PC running RSNetworx Network Path through the 1756-ENBT, Logix system Backplane and then point to the 1756-CNB. Edited by dmargineau

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"I have the RSnetworks for Controlnet installed on my computer, but I don't know if we have an interface to connect a PC for configuring Controlnet." Yes you can go online with RSnetworks, if you connect to the Ethernet network for the system and open RSnetworks with RSlinx running you will be able to see the network. Click network and then click online, if you expand your Ethernet connection you will see the Ethernet comm. card. Expand that and you will see the plc rack, next expand the rack and you should see the plc the controlnet comm. card and the Ethernet card. Click on the Controlnet card and expand that. There will be an icon for the network, click on that and click OK. "If I swap out the 1756-CNB/D Master Controlnet card will I need to use RSnetworks for Controlnet to configure it?" You will need RSnetworks to configure the Controlnet card, if the card has not already been configured.

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Thanks dmargineau and Steve G. I will try your recommendations.

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I reconfigured the ControlNet chain about 2 hours ago and so far so good. Although sometimes things would be fine for about 8 hours or so. The configuration was was easier to perform than I expected. Also I replaced a BNC connector that on of the technicians found to be loose. I am using compression type connectors as I saw that they were recommended for humid areas and this area has gotten wet at times although we are working to prevent that. I will be recompessing the rest of the connections as I found that the instrucions that came with the compression tool don't yield the best results. Attached are some screen shots of how the configuration was when first starting out. This was the first time that I ran RSNetWorx. It came as part of RSLogix5000 Standard and the RSNetWorx portion is not activated. Is this supposed to activate with RSLogix or do I need to purchase a separtae activation for that? Do you know how the taps on the ControlNet work? They remind me somewhat of the AUIs that were used with Thick Ethernet. Can they be replaced with Tees (75 ohm version) like was used in Thin Ethernet?
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RSNetWorx requires a separate activation. I would definitely recheck all of your coax connections as poorly crimped connections will cause you nothing but headaches.

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I re-compressed all of the BNC connectors and in the process found a loose power connection to the Node 3 ControlNet interface. Later I reconfigured the Node 4 ControlNet interface. That was the one that was most recently replaced. I saw that the network update time for that unit was set to 20 mS and all the other nodes were 5mS yet all nodes basically perform the same functions. Also the high speed counter that was on that node was set to 5 mS. It didn't make sense to me that an I/O would be configured for a faster rate than the node interface it was connected to. Now everything is set to 5 mS. The node interface that was recently installed was version 4.1, while the other 2 were 3.1. Probably they were alll origionally 3.1

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You are right daba. The root cause of the problems is the wetness in the control cabinet. That is what lead to modules being changed, wiring being handled and corrosion issues. This cabinet is in an area that receives daily wash downs and the cabinet seals are deficient. I am in the process of upgrading the seals to prevent water intrusion during the washdown process.

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Hi all. Today when I saw the problem happen again I noticed that the status light on the last 1794-ACN15/C in the chain had changed from green to red. I was able to reset it by disconnecting the tap. Our expert in headquarters is recommending to reflash the firmware of the ControlNet card. When I check the properties of the various interfaces, this is what I see: According to the report that RSNetworx produces, the revisions are: Node 1(1756-CNB/D): 5.038 Node 2(1794-ACN15/C): 5.001 Node 3(1794-ACN15/C): 5.002 Node 4(1794-ACN15/C): 5.001 According to RSLogix the revisions are: Node 1(1756-CNB/D): 5.38 Node 2(1794-ACN15/C): 5.1 Node 3(1794-ACN15/C): 5.2 Node 4(1794-ACN15/C): 5.1 According to RSLogix the versions are: Node 1(1756-CNB/D): 5.1 Node 2(1794-ACN15/C): 3.1 Node 3(1794-ACN15/C): 3.1 Node 4(1794-ACN15/C): 4.1 Also in the device properties module in the module identity field, all of the 1794-ACN15/C are listed as mismatch. Checking with the area Technicians, this node has always been problematic for years, not just the month or so that I thought it was. Lately it seems to be worse though. Any recommendations?

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The "Device Mismatch" situation needs to be solved for a proper scheduling of the network. You will have to update the EDS Database on the PC running the RSNetworks; go to "http://www.rockwellautomation.com/resources/eds/ " and download all the files relevant to your network's configuration. Also try to update your RSLogix 5000 and RSNetworks for ControlNet revisions. There are firmware "collisions" between the two software copies. RSLogix 5000 Rev. 17.00 is what we've been lately running on all of our machines with no hiccups so far; at least 08.00 CPR7 should be the RSNetworx copy revision you are using. When done, within RSNetworks for ControlNet ONLINE file, run the EDS Wizard for every mismatch occurence. Once there are no anomalies within the RSNetworks ONLINE file, reschedule the network and if the "trouble-making" node is still acting up, replace the Flex adapter. Edited by dmargineau

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I would not only replace all the seals but if this cabinet is in a washdown or moisture rich environment I would consider installing some sort of positive pressure device with a dryer. I have had several apps where the washwater was not penetrating the cabinet but the changes in temp due to the wash water vs production temps were causing condensation inside the cabinet. Once I put in the dryers this seemed to resolve most of the issues. They are relatively inexpensive.

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Thanks dmargineau, I tried your recommendation but in reverse. I switched the trouble node flex io adapter with its neighboring node which has been trouble free. I went to the site you recommended, but din't find a ver 5.2 which is what one of the nodes is and the other 2 are 5.1. I was able to download the 5.1 though. I then used the EDS wizard with the find an download option and update the EDSs. Checked that all said they were updated with 5.1 file. Then updated EDS on all flex io. The mismatch I am seeing is actually in all the flex io adapters and is only reported in RSLogix. RSNetworx does not report any problems except when I run diagnostics. It complains about a minor watch dog fault in the cpu execution. The problem continued after this change. I just changed the CNet bridge from one with ver 5.001 FW to 10.007 FW and reoptimized. I will wait and see if it gives better results.

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Hi Shiner, That sounds like a great idea. We have a lot of places where we could use them. Where can I find them and how are they called. I have seen many coolers, but never driers. How do you seal the wireway or conduit entrances to create a positive pressure?

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What firmware revision is your CLX running? And what RSLogix 5000 software revision are you using to interface with it? Newer hardware has the tendency to not become fully operational when installed within a system which is controlled by older firmware processors; moreover, older development/configuration software is usually less efficient (if at all!) when interfacing with the latest generation components.

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Hi dmargineau, The RSLogix is V16.03.00 (CPR 9) The CPU is a 1756-L61 with revision 16.7 The RSNetworx for ControlNet is 9.00.00 (CPR 9) Flashing the CNet bridge didn't correct the problem

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Correction: The project running on the CPU is V16.03.00 (CPR 9) The RSLogix installed on my PC is V17.01.00 (CPR 9 SR 1)

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Well...this explains the displayed firmware difference within your RSLogix 5000 application file... It is a good practice to maintain the same Major Revision on both the CPU firmware and the RSLogix 5000 software you are using to interface with. You could either upgrade the CLX firmware to 17 or download and install RSLogix 5000 Rev. 16 on your PC. The latter will be my choice since "flashing" a CPU is always a pretty scary process. Firmware/Software Major Revisions 16 and 17 are "closer" than most consequent releases but not quite similar.

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http://www.balstonfilters.com/cabinet_air_dryers.html You don't necessarily want to seal the conduits, perhaps maybe to the I/O and control points, but leave the supply power conduit open to allow the air to flow out. If the cabinet is completely sealed, all you will accomplish is to pressurize a humid cabinet. Chemical action is faster at higher pressures so leaving the moisture a path to escape is the best way. Remember, you want to replace the humid air with dry air. There is a good FAQ on this site you can check out. There are other manufacturers out there as well. As far as the long integers go, if you are not comfortable doing that I have seen where, using the type of multi-counter setup Mickey recommends will work in this way: on the HMI create overlapping displays, using the two counters. The first counter should count up to 9999 and reset and also trip the second counter to add 1. now your display will show a 1 to the left and 0000 in the right. If you align them properly they will look like one numerical display with a max count of 32*** X 9999. This should give you more than enough counting capabilities. A little primitive, but if you are new to this and don't want to jump into the long stuff.......

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I do have version 16.03 of RXLogix installed on the PC and that is what starts up when I load the software for this PLC. I just meant that I have upto version 17.01 on the same PC.

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Your last post clears the firmware/software issue... . "...The mismatch I am seeing is actually in all the flex io adapters and is only reported in RSLogix..." This is a quote from one of your previous posts. Could you elaborate a little more?

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Hi dmargineau, Sorry for taking so long to get back to you. Attached are some RSLogix screen shots of what I see related to the mismatch: In the general tab of the 1794-ACN properties, the revision is listed as 3.1 and I can only change the minor (.1) and not the major number. In the module info tab of the 1794-ACN properties, the revision is listed as 5.2 and also says mismatch.

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1794-ACN15 C/D Rev.5.x hardware profiles are not part of RSLogix 5000 Rev.16.03.00 software package (Rev 4.x Only!). I believe RSLogix 5000 Rev.17.00 is the first Release which contains it. However, since your CLX carries Rev.16.xx firmware, installing RSLogix 5000 Rev.17.xx wouldn't solve your problem... I am running Logix 5000 Rev.16.03.00 (CPR9) and can't add a 1794-ACN15 Rev.5.x either... Try updating the Logix 5000 to Rev.16.03.03 which is the latest release. Follow "http://support.rockwellautomation.com/webupdates/product_list.asp" Either way, I don't really think this is your problem. Since it seems that the particular node has always been a "troublemaker", maybe the particular topology (layout, proximity to electrical noise, environment) is the culprit. One mention to your adapter configuration though; always try to maintain at least a "Compatible Keying" level for any piece of hardware profile (if not "Perfect Match"). Do not "Disable Keying" unless it is an emergency. Strange things could happen when the processor "doesn't care" what it communicates with.

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Origionally it was set to Compatible Keying, but I received a recommendation to change it to Disable Keying to try to avoid the fault. Changing the keying did not prevent further faulting. I will put it back to the origional setting this weekend.

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A Rockwell Field Service Engineer was here this past Saturday. He checked the signals on the Control Net and found them to be normal. He inspected the connections of the cabling and saw some problems with the way they were installed and replaced all the connectors. Also in the process of replacing them, he noticed that there was some oxidation on the center conductors of some of the cables, but didn’t think that it would cause a problem especially since the signals look good. We will be replacing them all just to make sure. Also he had said the replacements must be AB or Belden ControlNet cable. What is currently installed is another brand of RG6 quadshield that is labeled as ControlNet cable. The cable that I had tried as areplacement when we first started seeing this problem was regular RG6 which didn't solve the problems we were seeing, so I switched back to using the origionally installed ControlNet cabling after repairing one of the cable ends. Next he upgraded the firmware of the ControlNet bridge from 10.7 to 11.4. Also when he checked the AB firmware compatibility table he found that the firmware of the 1794-ACN15/C node adapters which were at 5.1, 5.2 and 5.2 were not compatible with the firmware in the PLC CPU which is 16.7. He downgraded all of them to 4.3. We cycled the system for about 30 to 40 minutes and we got a fault on node 4 which is the origional problem. Next he change the network schedule from 5 mS to 3 mS and the problem node interface and high speed counter also to 3 mS. Prior to that, everything was at 5 mS. We cycled the machine for about 1.5 to 2 hours and we got a fault. (I can’t say for sure if the problem is better as the amount of time between faults has always been highly variable.) I notice that all the status lights were green after a fault, but in the ladder logic that is checking the status word of the 1794-ACN15/C node adapters a 255 is being recorded and the fault counter incremented. Today I did some additional cycling of the machine and again it faulted after about 1.5 to 2 hours. This time I saved the program when the fault occurred to save the tag values. Also I checked the 1794-ACN15/C node adapters and high speed counter properties after the fault occurred. The node adapter says: it has a minor fault that was recoverable, and that there was a mismatch. I went and changed the version in RSLogix from 10.7 to 11.4 to match the new firmware. The High speed counter listed an “Unexpected Module” fault. This may be related to the problem, but I don’t know what it means. Attached are the screen captures of what I saw today. Any recommendations on what we should try next?

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