Can Head-end module 140 NOM 212 00 be used in hot standby configuration? I would like to have another Modbus Plus port in addition to the one that is part of CPU module. If this is not possible please explain why, and are there alternative solutions.

 

From my experience, in a Hot-standby system the ModBus Plus address 'swap' only happens in the CPU port. However, it can also happen in the ModBus TCP link provided by the NOE771 modules. If you need another Hot-standby connection then this might be your solution. Good luck.

 

Depending on your application, you won't need MB+ address swap in the case of a switchover between both CPUs. In that case it is possible to add one NOM module to each CPU backplane. The only problem is that the HSBY system won't verifiy the health of the NOM module. It means that in the case of a NOM failure, the main CPU won't change to the standby CPU.

But you can avoid that problem writing a few lines in your application code. You can observe the health of the NOM module and in the case of a failure force a switchover by the internal bit of the HSBY command word.

Some customers have done it here in Brazil succesfully.

 

Reply received on 21 January 2003:
===
CASE #621466:email------HSBY of 2x 984 785E each with one S985

Meir Saggie,
In answer to your inquiry please be advised of the following:
Quantum-HSBY systems do not monitor the health or integrity of MB+ communications. Similarly, they do not monitor the health of a NOM card. As such, failure of a NOM card will not necessitate a switchover. If the NOM card fails, you will not be able to communicate to the affected CPU via that card.
Please feel free to contact us at your convenience if you have any further questions.

Regards,
US Help Desk
Schneider Electric
[email protected]
===
end quote.

Meir

 

The mod bus does have an expnsion module which allows for an additional port.

 

Manual Quantum Hot Standby Planning and Installation Guide 840 USE 106 00 Version 4.0 (31002766 02) reads on page 27:
Minimum Module Versions to Support 984 HSBY... "140 NOM 2xx 00 version 2.1" - so this module is supported in HSBY.

You should also follow the advice on page 61:
===
Note: The order of the modules in the backplanes must be the same.

The rotary address switches on the back of each controller are set. The controllers may have different addresses. It is strongly recommended that the rotary address switches be set to the same address to eliminate any network address conflicts. The same advice applies to the NOM. For details on setting the switches, see the Quantum Automation Series Hardware Reference Guide or the Remote I/O Cable System Planning and Installation Guide.

===
Meir