adroit
Member
Hey guys, I'm super new to troubleshooting PLCs and was hoping I could get some guidance
I've got a machine I'm commissioning and it's kind of a stupid situation
I was meant to commission it after it was installed by an installation crew from another state who had to leave the machine partially installed/assembled when the COVID situation sent them packing. I started working on the machine in the 2nd week of May. When I saw the machine after the crew left in march, the machine was energized and the HMI was in its screensaver mode, if I recall correctly.
I wasn't allowed back on site until May because of the end user's COVID restrictions. Because I needed to finish mechanical assembly before trying to run the machine, I didn't even look at anything electronic in the control cabinet. I literally just deenergized the machine, got to work bolting some stuff on, connecting some pre-wired connectors, etc.
After I was done with the installation, I energized the machine and my HMI did not turn on. I find its fuse is blown. I deenergize machine, replace fuse, energize machine, go through equipment vendor reset/rearm procedure, and I have an alarm for one of my VFDs.
Guided by vendor, I find that the ribbon cable for my VFD's communication module had burned out, and also had apparently been routed incorrectly into back cavity of the VFD where it may have gotten hot / been eaten by a cooling fan. The VFD shares the 4a GMA fuse that blew for its 24VDC circuit into the Safe Torque Off Board
They send me a new comm module and ribbon cable, preprogrammed from factory. I replace them, energize machine, reset/rearm -- same alarm
They send me a preprogrammed VFD and comm module as an assembly. I replace VFD, transfer Safe Torque Off board from old unit to new unit, same alarm.
This is when it gets clear this is completely beyond my depth and also the depth of the guy I'm working with at vendor tech support. I don't know what could be relevant information so I'll just share some of my findings and ask what you all think maybe could cause something like this, or what kinds of things I could look at, because I'm completely at a loss and am waiting to hear back from vendor programmer to see if maybe it's a programming issue?
Machine components:
Allen Bradley CompactLogix 5370 1769-L16ER-BB1B (run, ok, and NS solid green, link 1 and link 2 flashing green rapidly, I/O light flashing green slowly)
5 x Allen Bradley 1734 IB8 (network and module status lights are all solid green, input status lights work with corresponding inputs)
3 x Murr remote IO modules (MS and NS solid green, the ethernet port that goes to CompactLogix has solid green and solid orange status lights on it)
Panel View Plus 7 6" HIM (I believe the ethernet port status lights are solid green and solid orange but I didn't make note of that; the IO display on HIM correctly shows IO status from all IO on PLC, expansion modules, and Murr units)
PowerFlex 70 with 20-COMM-ER and Safe Torque Off Board (STS light flashing yellow; Port, Mod, Net A flashing green; LCD display shows "Stopped"; digital inputs into this VFD are correct and I have 24VDC across terminals 6 & 8, and 24VDC across 3 & 4 on safe torque off board--under these conditions pins 1 & 2 read "open" which is correct per AB literature on Safe Torque Off Board; when machine is deenergized pins 1 & 2 read closed, so I know the STO is at least doing *something*; the ENABLE jumper was removed when I installed the Safe Torque Off Board, and obviously I removed the red jumper from pins 1 & 2 of STO connector)
There is an ethernet switch that the Powerflex 70, Panel View Plus 7, and CompactLogix are all connected to. The other ethernet port for ComactLogix goes to the Murr remote IO unit
I am able to connect to the network and see all of these components on the network with Connected Components Workbench, but I can only connect to PowerFlex 70 because I don't have software licenses for getting into the PLC or HIM. I am able to access Murr modules via my web browser. All of these components are on the network with the correct network settings per the tag on the control cabinet door. My powerflex 70 programming is correct per what the equipment vendor gave me (comparison checks out as identical)
So, basically, my powerflex 70 is receiving the digital inputs it needs to run, but it won't run. the I/O light on PLC is flashing like it isn't seeing something on the network, but I'm seeing everything on the network, and clearly the HIM is communicating with the PLC and expansion/remote IO modules because their statuses are correctly reflected on the HIM IO display
I verified all of the components for inputs into PLC are working properly in reality, and that the PLCs are getting correct inputs based on observable reality (laser sees reflector, limit switch is/isn't hitting a striker, prox is/isn't seeing its target, contact relay is/isn't energized, etc.) and also whether that component is normally open or normally closed
When I force my PowerFlex 70 to run by pressing the red button and then the green button, it rapidly switches back and forth between "Fwd" and "Rev" and "chatters" the motor it controls
I found this in the installation instructions for my Powerflex 70:
I'm thinking that maybe the programmer messed up in his programming and the Powerflex 70 is getting conflicting logical results (fwd and rev) at the same time, but I'm not seeing "DigIn CflctB" on my LCD display. I'm just getting the yellow flashing STS light. Drive status 2 (parameter 210) is xx00000000000001, for what that's worth
Some of the PLC inputs for the machine itself have confusing names, and are logically "inverted" or whatever--there are 2 inputs for "Process up" and "Process down" that are for normally closed limit switches (currently it is in the "down" position in reality, and I/Os reflect that) and there are two inputs for "Dispenser up" and "dispenser down" that are normally open proxes, but on the HIM these are also called "Process up" and "Process down"
Am I way off base thinking this could have been some human error where programmer named different PLC inputs the same thing and got them mixed up when he was creating the programming, creating logical contradictions that are forcing this Powerflex 70 not to run unless I manually force it to?
Or is there something really stupid I'm overlooking here?
It's just completely beyond my depth and I've spent a week on the phone with the equipment vendor tech support and feel like I've gotten nowhere on this
I only have Connected Components Workbench and RSlinx Classic Lite (or whatever the free version is called) and to be honest I had never downloaded or used either until encountering this issue on this job. As far as I know, I have no way to connect to the PLC or HIM without paying for the software licenses, and my employer doesn't seem to keen on doing that (I don't blame them--I don't know how to use the software anyway!)
Thanks in advance for any guidance you can give me
Even if you just point me in the direction of where I can look to learn more about this stuff, it would be greatly appreciated
I've got a machine I'm commissioning and it's kind of a stupid situation
I was meant to commission it after it was installed by an installation crew from another state who had to leave the machine partially installed/assembled when the COVID situation sent them packing. I started working on the machine in the 2nd week of May. When I saw the machine after the crew left in march, the machine was energized and the HMI was in its screensaver mode, if I recall correctly.
I wasn't allowed back on site until May because of the end user's COVID restrictions. Because I needed to finish mechanical assembly before trying to run the machine, I didn't even look at anything electronic in the control cabinet. I literally just deenergized the machine, got to work bolting some stuff on, connecting some pre-wired connectors, etc.
After I was done with the installation, I energized the machine and my HMI did not turn on. I find its fuse is blown. I deenergize machine, replace fuse, energize machine, go through equipment vendor reset/rearm procedure, and I have an alarm for one of my VFDs.
Guided by vendor, I find that the ribbon cable for my VFD's communication module had burned out, and also had apparently been routed incorrectly into back cavity of the VFD where it may have gotten hot / been eaten by a cooling fan. The VFD shares the 4a GMA fuse that blew for its 24VDC circuit into the Safe Torque Off Board
They send me a new comm module and ribbon cable, preprogrammed from factory. I replace them, energize machine, reset/rearm -- same alarm
They send me a preprogrammed VFD and comm module as an assembly. I replace VFD, transfer Safe Torque Off board from old unit to new unit, same alarm.
This is when it gets clear this is completely beyond my depth and also the depth of the guy I'm working with at vendor tech support. I don't know what could be relevant information so I'll just share some of my findings and ask what you all think maybe could cause something like this, or what kinds of things I could look at, because I'm completely at a loss and am waiting to hear back from vendor programmer to see if maybe it's a programming issue?
Machine components:
Allen Bradley CompactLogix 5370 1769-L16ER-BB1B (run, ok, and NS solid green, link 1 and link 2 flashing green rapidly, I/O light flashing green slowly)
5 x Allen Bradley 1734 IB8 (network and module status lights are all solid green, input status lights work with corresponding inputs)
3 x Murr remote IO modules (MS and NS solid green, the ethernet port that goes to CompactLogix has solid green and solid orange status lights on it)
Panel View Plus 7 6" HIM (I believe the ethernet port status lights are solid green and solid orange but I didn't make note of that; the IO display on HIM correctly shows IO status from all IO on PLC, expansion modules, and Murr units)
PowerFlex 70 with 20-COMM-ER and Safe Torque Off Board (STS light flashing yellow; Port, Mod, Net A flashing green; LCD display shows "Stopped"; digital inputs into this VFD are correct and I have 24VDC across terminals 6 & 8, and 24VDC across 3 & 4 on safe torque off board--under these conditions pins 1 & 2 read "open" which is correct per AB literature on Safe Torque Off Board; when machine is deenergized pins 1 & 2 read closed, so I know the STO is at least doing *something*; the ENABLE jumper was removed when I installed the Safe Torque Off Board, and obviously I removed the red jumper from pins 1 & 2 of STO connector)
There is an ethernet switch that the Powerflex 70, Panel View Plus 7, and CompactLogix are all connected to. The other ethernet port for ComactLogix goes to the Murr remote IO unit
I am able to connect to the network and see all of these components on the network with Connected Components Workbench, but I can only connect to PowerFlex 70 because I don't have software licenses for getting into the PLC or HIM. I am able to access Murr modules via my web browser. All of these components are on the network with the correct network settings per the tag on the control cabinet door. My powerflex 70 programming is correct per what the equipment vendor gave me (comparison checks out as identical)
So, basically, my powerflex 70 is receiving the digital inputs it needs to run, but it won't run. the I/O light on PLC is flashing like it isn't seeing something on the network, but I'm seeing everything on the network, and clearly the HIM is communicating with the PLC and expansion/remote IO modules because their statuses are correctly reflected on the HIM IO display
I verified all of the components for inputs into PLC are working properly in reality, and that the PLCs are getting correct inputs based on observable reality (laser sees reflector, limit switch is/isn't hitting a striker, prox is/isn't seeing its target, contact relay is/isn't energized, etc.) and also whether that component is normally open or normally closed
When I force my PowerFlex 70 to run by pressing the red button and then the green button, it rapidly switches back and forth between "Fwd" and "Rev" and "chatters" the motor it controls
I found this in the installation instructions for my Powerflex 70:
I'm thinking that maybe the programmer messed up in his programming and the Powerflex 70 is getting conflicting logical results (fwd and rev) at the same time, but I'm not seeing "DigIn CflctB" on my LCD display. I'm just getting the yellow flashing STS light. Drive status 2 (parameter 210) is xx00000000000001, for what that's worth
Some of the PLC inputs for the machine itself have confusing names, and are logically "inverted" or whatever--there are 2 inputs for "Process up" and "Process down" that are for normally closed limit switches (currently it is in the "down" position in reality, and I/Os reflect that) and there are two inputs for "Dispenser up" and "dispenser down" that are normally open proxes, but on the HIM these are also called "Process up" and "Process down"
Am I way off base thinking this could have been some human error where programmer named different PLC inputs the same thing and got them mixed up when he was creating the programming, creating logical contradictions that are forcing this Powerflex 70 not to run unless I manually force it to?
Or is there something really stupid I'm overlooking here?
It's just completely beyond my depth and I've spent a week on the phone with the equipment vendor tech support and feel like I've gotten nowhere on this
I only have Connected Components Workbench and RSlinx Classic Lite (or whatever the free version is called) and to be honest I had never downloaded or used either until encountering this issue on this job. As far as I know, I have no way to connect to the PLC or HIM without paying for the software licenses, and my employer doesn't seem to keen on doing that (I don't blame them--I don't know how to use the software anyway!)
Thanks in advance for any guidance you can give me
Even if you just point me in the direction of where I can look to learn more about this stuff, it would be greatly appreciated