Fahim shah

hotstandby Modicon Quantum Hotstandy

4 posts in this topic

dear all

 i have  2 NOE cards (network TCP/IP card) on a modicon quantum hotstandby system, one NOE install at primary CPU and one on secondary CPU. both NOE cards communicate with InTouch through same switch. the problem is that i can't write data to the plc whenever both NOE card are on the network. when i remove the standby controller from the network i can write data to the plc.

the switchover of hotstandby is tested and working fine.

can anyone tell what i am missing here.

thanks i advance

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Posted (edited)

The Standby PLC have IP address + 1. For example, 191.168.1.1 for the primary and 192.168.1.2 for the standby. Maybe you write data to the standby, and the primary rewrite it every scan. I think both the PLC are standby if you remove CHS card and you can write data.

Edited by leon78

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Posted (edited)

both plc are not in  standby mode,  it is confirmed only one at time is in primary mode. suppose i have controller A in pri mode i can only read & write data to plc only if my standby is disconnected from network. if i disconnected  the pri controller from network and connect the secondary controller to the network in this case now i can only read data from plc can't write to it which is good. but if i connect both pri and hotstandby controller to the network now i can only read. i have configure both NOE cards ip address to the 19.168.1.101 and i am writing to  same ip address.

 i am using 140 NOE 211 card and quantum 140 CPU 534.

i think my NOE didn't support Automatic IP swap over on Hotsatandy

Edited by Fahim shah

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As was mentioned before, the IP address for the standby should default to the primary plus one.  They should NOT be set to the same address, that would create a duplicate IP address error on the network.

Hot standby is a funny system, as it swaps the addresses when the primary and standby switch roles.

Why would you be writing to the standby anyways?  The primary should be keeping it up to date.

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