National Instruments SCADA and Mitsubishi FX

  • Thread starter Andrew Hodgekins
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Andrew Hodgekins

I have been trying to link a Mitsubishi FX-24MR PLC to the National Instruments Lookout SCADA software using the FX-485ADP and FX-485PC-IF modules, with no success. I'm sure that I have wired the serial cable correctly, as the RD light is blinking on the PLC comms module - the PLC never sends any data back however, and all I get is timeout errros. Can anybody help?

Rod Doolittle

Communicating with the FX2N processor from Mitsubishi can be a bit frustrating at first.

The processor will not send data back until it has received data, at that point it will send its data.

You have to enable the RS command ( RS D4150 K20 D4170 K20 ) example of setting up the RS command to send 20 (Bytes) of data starting with register D4150 and to receive 20 (Bytes) of data starting at D4170. On thing that the manuals don't tell you is that the send and receive quantity is in bytes and not words.

You then have to SET M8122 ( Transmit Data Request ). This bit will be reset automatically when it has completed sending its data.

You have to manually reset M8123 ( Receive Data Complete ). Typically I just say that IF M8123 THEN RST M8123.

Are you moving the correct port parameters into D8120 ( Port Parameters ) on the initialization of your processor?

Another thing, you may have to write a script in your HMI to only poll for data every 1/2 a second or so. It depends on the number of drops and the amount of data. You can get that value to less than a 1/4 of a second or better.

You may also want to do some "Token" passing to run this. Have the HMI send the token and when the PLC sees the token, then it will transmit back. This would be the quickest way to do it.

If you have any questions and you would like to contact me directly, please feel free to do so.



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Steven Landau

We had serious problems trying to get these modules to work for comm with a Intellution Driver. 4 days of trying we would get it to start comm, but it would intermittently stop, Then to get it started again I needed to clear plc memory and re-load software. (Something to do with confi of ADP daughterboard.

Our solution was to use the programming port RS232 instead of 485 with the Red 485/232 converter cable purchased from Mitsubishi. You can get second programming port with DIN connector to fit in place of the ADP board.

It worked first off. We were using Kepware OPC driver. Ask NI to connect you with someone who is using your hardware combination with lookout.

Steve Landau
VP Controls & Automation
92 Montvale Ave
Stoneham MA 01890

Office: 781-438-3337
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Check your request string being sent to the FX. A good example is in the manual that came with the PC-IF modual. There is even a basic program example.

Preston Todd Johnson

have you contacted National Instruments customer support, [email protected], or their UK office at [email protected], 44 0 1635 523545. National Instruments has an excellent support group and to back them up a rapid response team that can dig deaper than the manuals. They are very good, with adequate time, at getting to the bottom of issues like these.

Good Luck

Todd Johnson
Interspace Electronics

Andrew Hodgekins

I think I've sorted it now - kind of. After being told - by my Mitsubishi dealer no less - that the PLC would work with the 485ADP module as it has the little comms port on the side, I have since found out that it won't. The PLC is a version 2.00 - the 485 modules require version 3.30 of the CPU or later. Having taken the thing to bits, it looked like I should be able to upgrade by simply replacing the top circuit board; but Mitsubishi have told me that they don't offer this as an upgrade path. As a result we're going to have to buy new version 3.30 FX's to replace the ones we have, and use the others where we don't need the SCADA to monitor them.

Thanks to everyone who's suggested things so far - hopefully it should all work when I get a new PLC to play with in a few days.

Andrew Hodgekins
Hartington Conway ltd.
[email protected]