Compactlogix message

I have a compactlogix 1769-L32E, PV600+ and 3 Lenze drives (each drive fitted with a Ethernet IP module)
Both the compactlogix PLC and the pannelview+ are connected directly to a network switch and the drives are daisy chained together then connected to the switch with a single cable
when the system is as above everything works fine
But
I have to read data from another compactlogix 1756-L62 fitted with a 1756-1756-ENBT card (Version3.9)
So in my project i have added a connection for a 1756-ENTB/A module and added a MSG instruction (CIP Data table read) in the program

When the PLC is in run mode and the PLC that i read a data from is not on the network (i.e M/C switched off) then one of the drives (the one at the end of the daisy chain) has an intermittent comms timeout error, this error occurs every 5-15 mins

if the connection to the PLC that i read data from is inhibited then everything works fine.

I think this may be caused by RPI times, does anyone have any other opinions?
is there a common method to set/check RPI times as all are at default or am i missing something

Is there anything else i should be checking

Thanks in advance for any help
Andy

It's possible that the drive timeout is due to a capacity problem in the 1769-L32E. You should be able to figure that out based on the diagnostic web pages for the 1769-L32E Ethernet interface.

Those will show you the number of TCP and CIP connections the controller is actively using, as well as the packets per second the Ethernet interface is handling. The web pages include notes about the maximum capacities of each value (like 32 CIP connections).

If the devices you describe are the only devices the CompactLogix is communicating with, you very likely haven't exceeded its connection or bandwidth capacities.

How does the "daisy-chain" between the Lenze drives work ? The communication error might be due to something in the wiring, and the timing of it might be a coincidence.

You don't need the remote 1756-ENBT and controller in the I/O tree to use a MSG instruction. The I/O tree object is only necessary when you're going to use Produced/Consumed Tags, and in fact it does consume some connection resources.

What I would do is Inhibit the connection to the remote 1756-ENBT and controller, but leave it in the I/O tree so that it makes it easier to select the remote controller in the MSG instruction Path field. The Path can always be determined manually, but it's easier to just select the target from the I/O tree.

Thanks for your reply Ken,
Each Lenze drive has an Ethernet/IP module, this module has 2 ports, these ports are effectively a small network switch and i am using 1 port as a network in and 1 port as a network out, the connection cables are all standard cables.
I have ended up removing the 1756-ENBT from my network tree and just entering the path as a comma separated number value, since then i have had no further issues.
Originally i was going to use produced / consumed tags but plans changed as this is not what the customer had in mind, that was why i originally left the connection in the network tree.

although the issue is now fixed i must admit i am still curious about the cause as the loss of comms could be coincidence and a side effect of something else but unfortunatly i do not have the time to investigate furthur at this point

Thanks again

Andy