AB Micro800 & Freewave fgr2-c-u radio

[584Zap]

I'm installing a SCADA system that consist of reading data at a Wastewater Treatment Plant, Elevated water tank and 3 lift stations. My master site is the WWTP that we are using a AB Micro870 at that location. At the rest of the sites we are using AB Micro830 at the other 4 sites. For communication we are using Freewave FGR2 - 900Mhz radios and are using serial communication. The Master radio is located at the WWTP, at the Elevated tank is the repeater site with the 3 Lift Station radios as slave radios. The radios are existing radios, except for one, that a Freewave tech had me verify that they were working using Tool Suite and other than having to raise the antennas for signal strength, that was the only issue. We decided to stay with the Freewave radios to help the city save on cost!!!!
The problem that we are having is that we are getting data back from the slave radios and repeater site but the data is not correct and it keeps changing even though at this point we are forcing set inputs from each site. We have taken the master PLC and a lift station PLC and put a serial cable between each directly and used the "Receive/Transmit" wiring setup and are able to run our program with no problems. On the radios we have played with the Subnet settings outlined in the FGR2 manual setup but have had no luck. We have been talking with radio tech support but all we keep getting is to send an hour worth of data to them and wait about 2-3 hours before they call us back to change a setting but still nothing works. We believe that we are having a radio setup problem but cannot find it.

 

[drbitboy]

What protocol is used to transfer the data over the radio and serial lines? Does it include either a checksum or other redundancy check? Can the wired serial and radio serial data be run in parallel? Can a spare radio be employed to sniff the transmitted data?

 

[Saffa]

As the Dr said... what protocol? Since you are using serial, each remote site needs to have a unique address, and you need a protocol, like Modbus or DF1 that supports that. Otherwise, all sites will try and reply to the same message, which could explain your unexpectedly changing data... which slave gets through would not be deterministic.

I have not done much at all with the Micro 800 series. Have you written some kind of cyclic polling routine to message each remote site in turn? It would be useful if you could post the following:

PDF of your code showing how each site is polled from the micro 870.
Screenshot of the serial port setup of each PLC (or at least the master, and two remotes).

You may well have a radio issue, they can be tricky with serial data... but let's confirm the PLC side first, which is normally the easy part.

 

[diat150]

freewave are rock solid. If you are unsure of what the settings should be, use the toolsuite to create a new point to multipoint radio network with your master and each slave. all you should have to change is in the baud rate tab....your baud rate and serial type stuff, and then there is a setting called modus rtu which should be 1 if you have modbus devices on the radio network. then go download to each radio.



That should be it. When I have trouble with existing networks this is what I typically do. People think they know what they are doing and mess up the settings.


This is if you are using modbus. I would reference the manual to see if you need any other setting change for df1 if that is what you are using.

 

[584Zap]

I’m using the MSG_CIPSYMBOLIC block through the micro 870’s serial port. The Freewave’s are set to RS232 and all bauds match at 19200 in the radio and plcs. The messages to the slaves are all SINT[10] data arrays. My msg for the repeater site seems to work correctly but the remotes don’t seem to make it through the network back to the master. I can modify the subnet in multipoint settings related to the repeater radio and I can get the slave message to complete properly but the slave on the repeater doesn’t complete correctly.

 

[OkiePC]

I am not familiar with the Micro800, but we do a lot of serial radio telemetry with the Micrologix series and this requires choosing a serial port protocol that supports a station ID number (node number) like DF1 Radio, DF1 Half Duplex, or Modbus.

"CIP Symbolic" sounds more like a Studio 5000 type of driver, so I would steer you towards the settings for the protocol used on the serial port to see if there is a Node Number or Station ID number that can be set with that protocol and if not, you might need to switch to a different protocol.