We are usiing PLC 5/40 with hot backup ,now we are facing problem as in RSLInx it is showing only one processor also as i try connect node1 it give mesage "cannot get connected with onlinePLC" while i am able to connect to node 0 .Hot backup system is working properly.what could be probelem.

What kind of interface device are you using to get online ? A 1784-KTX, or 1784-PCMK ? What version of RSLinx, and what is the node number you're assigning to RSLinx ?

Going online with PLC-5's over DH+ is really pretty straightforward. Tell us more about your system and maybe somebody will be able to help.

What does A-B tech support say about this ?

I am using 1784-kt card for communication & RSLINX version 1.7.i have assigned node 0 to plc processor & 70,71 to workstations.
When i try to connect processor that in standby by RSLOGIX it shows this message: "CAN NOT GET CONNECTED WITH ONLINE PLC".

What's supposed to happen, Kelvin, is that you set both PLC-5's in the hot backup pair to the same DH+ node number (I've never seen anyone use Node 0; try Node 1).

The 1785-BCM module then forces the PLC-5's to behave differently; the Primary controller uses the assigned node number, and the Secondary controller uses the assigned node number + 1.

Can you see both the PLC-5's using RSWho ?

The 1785-BCM/BEM hot backup system isn't for beginners. Have you called Rockwell Automation support on this yet ?

By the way, RSLinx 1.7 is nearly five years old and may not work correctly with Windows 2000 or XP, if those are the operating systems you've chosen.

RSLinx Lite 2.41 is a free download !

Thanks for your reply, Yes i have assigned 0 address to both the nodes.& i am unable to see both PLC processors by RSWHO.I am using windows 95.