Serial Comms to A-B ControlLogix

B

Thread Starter

Brad Hite

Hello List,

I have encountered an interesting problem with an A-B ControlLogix PLC. The PLC in question is a 1756-L1 processor without any memory modules. The
system is in a 10 slot chassis with a ControlNet and Ethernet Comm module as well as a couple of local I/O modules. The ControlNet module is
communicating with 6 ControlNet Flex I/O drops.

The system is operating normally. However, I cannot establish a programming connection with the processor through the serial port. RSLinx is configured correctly and can "see" the processor, backplane and modules.

I am receiving two (2) different error messages from RSLogix-5000 when I attempt to go On-Line with the controller through the serial (DF1) port.
error #1: Failed to go online with the controller. No open connection. error #2: Failed to go online with the controller. Invalid communications path or controller not responding.

I have double and triple checked RSLinx and RSLogix-5000. I can go On-Line with other ControlLogix and FlexLogix processors through their serial ports just not this one processor.

I have double and triple checked the serial port configuration stored in the project file for the processor. All settings are normal factory default
settings.

Anyone got any idea or encountered this problem before?

Bradley G. Hite
Intertech Inc.
mailto:[email protected]
http://www.myplc.comTeaching Practical Skills for a Technological World
 
I've seen the "invalid communications path" when (1) there's really an invalid comms path, because
I've used a multi-hop (Enet/backplane) path to go online last time I used the project, and haven't
re-defined the path using the Who Active Go Online function, (2) the RSLinx DF1 driver is incorrect about Device Type, because I last used it on an SLC. Autoconfig fixes that right up.

Another I've seen in classes is the mistake of browsing "too far" through the serial port and making a loop... their comms path is Ch.0 -> Backplane -> Controller instead of directly to Ch. 0.

If you have CNet and ENet then of course you can go through one of those paths to check the actual
online configuration of the serial port.

Is the Ethernet communications particularly busy? I've seen instances, actually with ControlNet, where PanelView stations used up so many logical connections that the controller
didn't have any more to connect to my programming PC.

Good luck,

Ken Roach
RA Seattle
 
Hello Ken,

Thanks for your reply.

> > "I can go online with other ControlLogix and FlexLogix processors
> > through their serial ports just not this one processor"
>
> I've seen the "invalid communications path" when (1) there's really an
> invalid comms path, because
> I've used a multi-hop (Enet/backplane) path to go online last
> time I used
> the project, and haven't
> re-defined the path using the Who Active Go Online function,

Agreed. I have had the same problems. However, that is not an issue in this case.

> (2) the RSLinx
> DF1 driver is incorrect
> about Device Type, because I last used it on an SLC.
> Autoconfig fixes
> that right up.

Agreed. This can be a problem but as I pointed out in my original post RSLinx is correctly configured for communication with a Logix controller serial port.

> Another I've seen in classes is the mistake of browsing "too
> far" through
> the serial port and making
> a loop... their comms path is Ch.0 -> Backplane -> Controller
> instead of
> directly to Ch. 0.

I have seen the same thing happen. However, again that is not the problem with this particular circumstance.

> If you have CNet and ENet then of course you can go through
> one of those
> paths to check the actual
> online configuration of the serial port.

I thought the same thing. However, I cannot assign an IP address to the Ethernet module. When I use RSLinx to configure the Ethernet module
(Communicating through the serial port on the processor that I cannot go On-Line with) I get an error message. The error message is;

Unable to communicate with the selected module.

Possible causes for this could be:
-Loss of power to module
-Not connected to network
-Module too busy to respond
-Invalid communications path

None of the above errors make sense. The module is powered because I can browse to it in RSLinx. Module is connected to ControlBus network because I can browse to it in RSLinx. Module cannot be too busy because nothing else is connected to it. Communication path is valid because I can browse to it in RSLinx.

> Is the Ethernet communications particularly busy? I've seen
> instances,
> actually with ControlNet, where
> PanelView stations used up so many logical connections that
> the controller
> didn't have any
> more to connect to my programming PC.

I thought this might be a potential problem also. However, as I stated in the original post there are only 6 drops on ControlNet and the are all using Rack Optimized connections.

Any other thoughts anybody?

Bradley G. Hite
Intertech Inc.
mailto:[email protected]
http://www.myplc.comTeaching Practical Skills for a Technological World
 
Flash the firmware on the Processor.

The Processor firmware is in 'lock-step' with control logix programming version.

I.e. Version 8.02 ControlLogix5000 Software ships with (check the supplemental materials CD) a flash image to take your processor to 8.02.

Until I did that I could not go online, upload or download to my processor. Despite the fact that RSLinx apparently saw it.

Once the processor is flashed. You should be able to see all of the I/O modules on the rack backplane.

Slack
 
E

Eduardo Manuel C. Cipriano

Hi

I been with AB before fo 4 years as a Sr. Automation Engr. for Tech Support
what you could do is this:

Problem:
An error message is received when trying to go online or download to the Logix 5550 processor:
Failed to go online with the controller. Attached controller's revision incompatible with software.

Cause:
This error is caused by an older version of firmware in the 5550 processor that is incompatible with your current version of RSLogix5000 software.

Solution:
Upgrade firmware using the ControlFlash utility and new firmware. The ControlFlash tool and firmware files are included on the RSLogix 5000 CD. When the Autorun screen comes up after inserting the CD, choose "Upgrade Controller Firmware" to install ControlFlash. To run ControlFlash, select Start > Programs > Flash Programming Tools > ControlFlash. It will read the list of installed firmware on your system, and allow you to update any of those modules


anyway if you have any additional problem you could email me at

[email protected]

Eduardo Manuel C. Cipriano
Sr. Systems Engr.
Yokogawa Phils Inc.
 
Hello All,

I have some new info on my Serial Communication to ControlLogix PLC Problem.

To recap. I cannot connect to the processor serial port with RSLogix-5000 even though RSLinx is configured correctly.

I finally got the opportunity to stop the Process the ControlLogix PLC was controlling. Even with the controller in Program Mode (with the key switch). I could not connect to the controller. In frustration I unplugged the battery and powered the controller down erasing the program in the controller.

After powering the controller back up I was able to attach to the controller and download the program back into the controller.

I was then able to go ON-Line with the controller. Figuring I had the problem solved I put the controller into Run Mode. At this time I was still On-Line with the controller and could monitor, troubleshoot, and program it.

I then went Off-Line. During the process of going Off-Line I received an error message:
Communication Request Failed

After acknowledging the error message I was Off-Line. I then attempted to go back ON-Line and all of my communication problems were back. Now I cannot connect with the controller through the serial port again.

Again any ideas or thoughts about what is going on?

Bradley G. Hite
Intertech Inc.
mailto:[email protected]
http://www.myplc.comTeaching Practical Skills for a Technological World
 
D
The last problem you had, did your communication problem reoccur after downloading the program?

If it did, you may want to check the amount of memory available in your processor with a running program. With the ethernet, controlnet & the remote racks you may be having an issue with the amount of memory, which is easily fixed with an M1 module.

Just a thought,

Darren Ash
 
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