Peerlink status bits using ECOM100

[Scot]

I am setting up 2 plcs for 3 truck dumpers. The controls for 2 of the dumpers are in 1 building along with both PLCs. One PLC is a new Do-More (with ethernet) and the other is a DL260 (that was already in place). The 3rd dumper is being controlled by the Do-More with a C-More and some button inputs in another building (to provide visual access to the 3rd dumper during operation).
I left the existing DL260 in place operating dumper 2 as a redundancy.
I have 1 C-more in the main building between dumper 1 and 2 with the PLCs and controls. The Do-More is controlling the C-More screen switching for both dumpers and getting some of the data it needs from the DL260 to control the C-More. The Do-More is also controlling a ViewMarq display that we are making a weatherproof box w/ panel heater so we can place it outside the building where the front-end loader operators can see it.
All of this is still being built, but I'm nearly finished with the programming.

To get to my question: I saw where the Do-More has Peerlink status bits so I should be able to just check PL.B14Err (the DL260's ECOM100 is publishing to block 14 and subscribed to block 15 to receive data from the Do-More) to determine if the DL260 is online. Or, maybe it's the PL.B14Rate I need to check to make sure it's not 0? Then if there's a problem, I can show on the C-More that dumper 2 is offline.

But, how can I check from the DL260 to verify that the peerlink block it is subscribed to which is being published by the Do-More (block 15 in this case) is actually being updated so I can determine if the Do-More processor is offline and the DL260 should take over control of the C-More screen and the ViewMarq display?

[b_carlton]

When I need a verification handshake between two units I reserve 1 bit in the communication block for each direction.

One side takes the bit it reads then outputs it unchanged to the write block.
The other side does the same thing except it inverts it between the read and the write.

Then each unit has a pair of timers, one enable by the NO of the bit and thee other enabled by the NC of the bit.

Set the preset to sufficiently  more than the exchange time to prevent nuisance timeouts. If either timer times out there is a communication problem.

[Scot]

I had thought of something similar but without the handshaking. I was thinking of just making the first bit in the published block of each PLC set on whenever the PLC is on. But I didn't know if the bit would stay on or not if the publisher of that block went offline.

I suppose I could do something similar but have the bit pulse on and off then build a delay in the receiving PLC identical to a zero speed detection.