GE Fanuc 90-30 Modbus question...

I'm working with a GE Fanuc Series 90-30 PLC and am coordinating it through Modbus protocol to a MSA Ultima XE Gas Sensor with Modbus and I have two questions:

The first regards the 90-30 CPU. I set up a bench test with a spare CPU363 and am able to communicate with the unit. However, I will be installing this with a CPU360 in the field (the site is far away and I don't have a spare CPU360 lying around). With the CPU363, I can configure port 2 (rs-485) in the hardware configuration and using the CommReq function. However, when I look at the program they have with a CPU360 (this job is an add-on to a running program where the PLC cannot be shut down, i.e. no hardware config. download) there is no configuration for port 2. If I just use the CommReq function to set up port 2, will this work without shutting the PLC down?

And the 2nd question is, some of the registers from the gas sensor are formatted for single precision floating point. When I receive the data from the unit in the PLC and compare it to what is configured locally at the unit, they differ greatly. Do I need to convert the register to a floating point value and if so, how? I'm relatively competent with GE Fanuc programming but never had to use floating point so I'm not quite sure how to do this.

Any help is greatly appreciated. Thanks.

Pete

Unlike the CPU363 which has two serial ports, the CPU360 does not have any serial ports on the CPU module. I think you're going to have to wait until the end user can take some downtime and install a new CPU363 module to get RTU master capabilities. Either that or install a Horner HE693RTM705 module.

If you're not seeing the value that you expect from the floating point data, you may need to swap the low and high words. It's possible that the MSA device sends the words in the reverse order from what the PLC expects.

So are you saying that the 2 ports I see on the CPU360 are not functional and for decoration only?

Are you looking at an actual CPU360 or a picture? Catalog GFA-406, page 96, in the CPU360 column at the "Built-in Communication Ports" row states "One RS-485 port on power supply. Supports SNP". Series 90-30 installation manual GFK-0356Q, page 5-37 shows a picture of a CPU360 module with no serial ports. The next page shows a CPU363 module with two serial ports.

Ok. I see both of those. I believe I was mistaken before with the CPU360. We also have a CPU352 lying around and I was thinking of that one. So it looks like I will have to inform them that they will have to change the CPU or get a RTU Modbus master module and shut it down while we install it. Thanks very much for the info. Greatly appreciated.