WHICH PLC TO CHOOSE ?

[Guest Guest_JOE]

I am currently a Siemens TI505 plc user. I am upgrading my PLC system and trying to decide between choosing a Siemens S7-400 system and Mitsubishi-Q system. The Q-plc is a very recently launched plc, I believe it was launched in 2000. It uses a high speed (12Mbaud) USB link to the CPU as standard. This means that I dont need to disassemble my operator interface computer to install any communications adapters, as computers come with USB as standard. With the S7 I need to get a CP5611 card and install it and then set it up. They also have a serial comms module which runs a BASIC program which will allow me free control over the comms protocol. I dont think there is a comms card with the S7-400 that allows this. all comms funcvtion is controlled from the system program. I wonder does this limit the versatility offered to the user in creating and managing a protocol. For remote modem diagnostics, in the case of the Q-plc, I already have the RS232 port on the CPU. Then all I need is a modem and the programming software. In the case of the S7-400 I need to spend the best part of £1000 sterling on a teleservice adapter and teleservice software to add to my STEP7 software pack, before adding the modem. Does anyone have any good reasonds why I might go the way of the S7-400. I guess the technical backup and parts availability should be better in this case, considering that siemens and their distributors are ubiquitous.

[Crossbow 295]

I personally would use the Mitsu Q. It's a much smaller platform, and it's more powerful. Of course, I have many customers who are reviewing the Q for applications, and some of them are interested in the multiple CPU capabilities and expandability. Then when you add the fact that the Mitsu A series operator interfaces have an available module to connect them directly to the Q series backplane. This means it's a high speed communications, and it leaves the COM port free for other uses.