Hot Standby Question

[Newbie System Designer 0]

Hi, Just want to confirm if is it possible to add a modbus connection to a Hot Standby configuration (Quantum) with existing Remote I/O drops. The CPU Module is 140 CPU 67 160. I also used a Ethernet Module (NOE 771 01) for the network communication. The specs say that I should connect the CRAC Units via modbus cable to the CPU's. Is it possible since the CPU module has a modbus port? If yes, do I still need other modules (specifically for modbus connection) ? Hope that someone can help me. Edited 13 Apr 2009 by Newbie System Designer

[aggattapauer 2]

sure you can. You have an integrated modbus port. You could even configure the switchover of the addresses if the cpu swapped to the other.

[Newbie System Designer 0]

Correct me if I am wrong, will I use a splitter (for MODBUS) to be able to connect it on both primary and standby CPU?

[aggattapauer 2]

The modbus port master could have addresses from 1 to 119, automatically the modbus port standby will have address master+128. ie mb master = 1 mb standby = 129 So both ports could be connected to the same serial bus because their addresses are managed by the hot-standby system. You can use any modbus equipment but remember that the integrated CPU modbus port are RS232C so you need to configure previously in rs485. I don't know what you mean with "splitter", you have to create a multi-drop 485 bus. you could use i.e. the SCA62 and two cables VW3A8306 for connecting the quantum cpu's

[Modiconbob 2]

Modbus is an RS-232 serial comm link. You cannot "parallel" the connections. They must be isolated with a modem of some type. As mentioned the address' will (if selected to) be offset by 128.

[aggattapauer 2]

Just in case (see above) you have to convert your electrical signal from RS232 to RS485 link with for example the XGSZ24 RS232/485 converter (just to stay in Schneider house) or others