Melsec Driver issues

[RobertMiller-KR2]

I am using Version Fuxa-pro version 1.2.7 with the Melsec driver. I am using a iQ-F PLC. I set the SLMP connection up on port 1240. I cannot seem to make it work. It connects and reads the status for the tag once then I get a polling overload.

Any assistance would be appreciated. I may be able to assist with any development with this driver as I worked for Mitsubishi for 15 years including a couple as director for CLPA-Americas.

[RobertMiller-KR2]

I have gotten it working mostly, @unocelli according to the mcprotocol.js sample when reading or writing register addresses if they are other than WORD values the address needs to be modified when sending it to the variable. IF I have D1000 in the plc and I want to read it as REAL, I have to enter DFLOAT1000. To me the correct way yo handle this would be to just enter it a D1000. If I set the Tag to be a REAL it should modify it to DFLOAT1000 when sending to to mcprotocol.js variable. The same thing happens with Double data types. a Double Word needs to be addressed as DDINT1000 if Address D1000 is a double integer. If its a String it needs to be DSTR1000, (length of string) This could be another setting for the tag (string length). I will be happy to try to make these adjustments although my Java programming skills are terrible.

[RobertMiller-KR2]

If anyone comes across this looking for help I thought I would add this so you can get your working as well. These are settings I have successfully used with a Mitsubishi FX5UC. It is actually using the SLMP protocol. There are some tricks

Here is the Driver Settings In Fuxa obviously set the PORT number to match the port you specify in GXWorks3

You will need to modify the mcprotocol.js file in Fuxa. its located at /usr/sopurce/app/FUXA-Pro/server/_pkg/mcprotocol/
set it to 3E frames (line 58),
set Ascii to 0 (line 57)
change line 1347 to writeResponse = theData.readUInt8(1);

Here are the Ethernet "External Device Configuration" in GXWorks3 (mitsubishi)
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Here are the settings I have used for the Tags. If you need other data types they are listed in the mcprotocol.js file starting at line 2072

[unocelli]

@RobertMiller-KR2 Thanks for the report, we need to investigate

[RobertMiller-KR2]

@unocelli Ive done quite a bit of updating to the Melsec driver. I would like to know the following.

1. I want to add a Debug switch on the driver setup window. Where does that file get generated from?
2. When trying to test for disconnection I get the below NPM error. I added code to the mcprotocol to handle timeouts and such. THe indicator for the driver shows it disconnects then reconnects (green indicator/yellow indicator/green indicator) but i think the NPM error causes it not to be able to actually get the data until restarted.
3. Here is the update mcprotocol.js file
   mcprotocol.js

0 verbose cli /usr/local/bin/node /usr/local/bin/npm
1 info using npm@10.8.2
2 info using node@v18.20.8
3 silly config load:file:/usr/local/lib/node_modules/npm/npmrc
4 silly config load:file:/usr/src/app/FUXA-Pro/server/.npmrc
5 silly config load:file:/root/.npmrc
6 silly config load:file:/usr/local/etc/npmrc
7 verbose title npm start
8 verbose argv "start"
9 verbose logfile logs-max:10 dir:/root/.npm/_logs/2026-05-06T02_01_39_103Z-
10 verbose logfile /root/.npm/_logs/2026-05-06T02_01_39_103Z-debug-0.log
11 silly logfile start cleaning logs, removing 1 files
12 silly logfile done cleaning log files
13 verbose stack Error: command failed
13 verbose stack at promiseSpawn (/usr/local/lib/node_modules/npm/node_modules/@npmcli/promise-spawn/lib/index.js:22:22)
13 verbose stack at spawnWithShell (/usr/local/lib/node_modules/npm/node_modules/@npmcli/promise-spawn/lib/index.js:124:10)
13 verbose stack at promiseSpawn (/usr/local/lib/node_modules/npm/node_modules/@npmcli/promise-spawn/lib/index.js:12:12)
13 verbose stack at runScriptPkg (/usr/local/lib/node_modules/npm/node_modules/@npmcli/run-script/lib/run-script-pkg.js:77:13)
13 verbose stack at runScript (/usr/local/lib/node_modules/npm/node_modules/@npmcli/run-script/lib/run-script.js:9:12)
13 verbose stack at #run (/usr/local/lib/node_modules/npm/lib/commands/run-script.js:130:13)
13 verbose stack at async RunScript.exec (/usr/local/lib/node_modules/npm/lib/commands/run-script.js:39:7)
13 verbose stack at async Npm.exec (/usr/local/lib/node_modules/npm/lib/npm.js:207:9)
13 verbose stack at async module.exports (/usr/local/lib/node_modules/npm/lib/cli/entry.js:74:5)
14 verbose pkgid fuxa-server@1.3.0-2738
15 error path /usr/src/app/FUXA-Pro/server
16 error command failed
17 error signal SIGTERM
18 error command sh -c node main.js
19 verbose cwd /usr/src/app/FUXA-Pro/server
20 verbose os Linux 6.6.87.1-microsoft-standard-WSL2
21 verbose node v18.20.8
22 verbose npm v10.8.2
23 verbose exit 1
24 verbose code 1
25 error A complete log of this run can be found in: /root/.npm/_logs/2026-05-06T02_01_39_103Z-debug-0.log