CLX L84E CIP messaging

I can't seem to get messaging to work between L84E CLX processor and a PLC5/40E processor.What would the path be?
Currently I have: processor,2,IP address.

With this path I get error code 16#0001 Connection failure

That path is generally correct; Port 2 is the built-in network port of a 1756-L8xE controller, and the target PLC/SLC/MicroLogix doesn't need a backplane + slot number "hop".

Have you verified that the PLC-5E firmware supports CIP ? "Dual stack" CSPv4 and CIP firmware was added to the PLC-5E and 1785-ENET about twenty years ago.

I can look up the technote that gives the exact Series / Revision information, but a very quick way to figure it out for sure is to use TCPING and see if it accepts a connection.

TCP Port 2222 = CSPv4, the classic A-B Ethernet
TCP Port 44818 = CIP, used by ControlLogix

both ports are open and the PLC5 firmware is k.3. I can read from the PLC5 using L7 processor and ethernet card with no problems.

Huh. An ordinary PLC-5 Typed Read or Typed Write should work exactly as you think.

Try doing a CIP "WHO" command to the same device, to read its Vendor/Class/Type/Revision. That will narrow down if this is a PCCC issue or a CIP issue.

Be 100% sure that's the correct target IP for the PLC-5E, and that it's physically reachable from the network where the ControlLogix is plugged in.