LURBY

Micrologix 1100 to Powerflex 525 Ethernet Comm loss

6 posts in this topic

I am setting up a Micrologix 1100 to communicate with a Powerflex 525 over Ethernet via messaging.  Everything works well so far.  I just realized though that if I lose my Ethernet cable for whatever reason I have no way of telling the PLC that there is a com loss.  I can monitor a drive fault as long as the cable is there but if the cable is disconnected or breaks the drive will fault and shut off but the rest of my machine will still keep going which would be bad.

Long story short is there something that changes state when I fail to communicate with the drive (be it reading or writing) that I can use some where else in the program to shut the system down?

Share this post


Link to post
Share on other sites

Lubby,

The manual for PowerFlex 525 with Embbed Ethernet, 520COM-UM001B-EN-E,  page 66 says the

A timeout value (in seconds) in the embedded EtherNet/IP adapter will issue a drive fault if a message is not received from the controller within the specified time. However, the controller has no way of detecting a loss of communications to the drive until the next cycle of explicit messages. This is another factor in the risk assessment.

 

Are you actually using explicit messaging to the drive?  About the best you can do is examine the error status of each message and then shutdown the machine.

Edited by pcmccartney1

Share this post


Link to post
Share on other sites

The easiest way I have found to detect com loss to a 525 drive is to reset the "Ready" bit in the input structure for the drive.  If the ready bit stays "Off" then there is no communications with the drive.

Use timers to trigger the reset of the "Ready" bit and to detect if the "Ready" bit has been off for long enough to signal a disconnection.

I set the timer for reset of the ready bit at the connection update rate * 1.5

I then set the timer to test if the drive is disconnected (i.e. Ready bit not on) at the connection update rate * 4525_Disconnection_Logic.thumb.png.85639d

Share this post


Link to post
Share on other sites

There's an error bit on the MSG instruction.

Share this post


Link to post
Share on other sites

Uhh, He's asking about Micrologix not controllogix. 
You can read and write assemblies from the MSG block under CIP Generic with service read assembly or write assembly.
There's no built in scanner in RSlogix500 like there is in RSlogix5000
I believe the Powerflex has a bunch of N registers you can read write to but that's there for SLC's and other forms of archaic voodoo.
 

Actually it looks like he's trying to follow "Publication 750COM-AT001A-EN-P - August 2012"

In which case the answer is in it. https://literature.rockwellautomation.com/idc/groups/literature/documents/at/750com-at001_-en-p.pdf

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now