Mitsubishi MELSEC Driver

Overview

MC protocol (3E / 1E) communication for Mitsubishi Electric PLC series (Q / L / iQ-R / iQ-F / FX).

Item	Value
`opc_type`	`MELSEC`
Implementation class	`plantpulse.driver.protocol.melsec.Melsec_34_Driver`
Library	iot-communication (`plantpulse.plc.protocol.melsec`)
read	✅ (batch mode)
write	✅ (Boolean/Integer/Long/Float/Double/String + `BIN[n]` word-bit RMW)
Security	None (direct TCP, assumes internal network)

OPC Registration Form

Field	Meaning	Example
`opc_agent_ip`	PLC IP	`192.168.0.60`
`opc_agent_port`	MC port	`5000` (Q/L default 1500)
`timecycle`	Polling interval (ms)	`1000`
`options.controller-type`	Series (`Q_L`, `QnA`, `IQ_R`, `A` — use `Q_L` for iQ-F/FX)	`Q_L`
`options.read-mode`	`single` (individual read per tag, default) / `grouped` (grouped batch read — minimizes round trips)	`single`
`options.batch-gap-words`	Allowed gap for word block merging in `grouped` mode	`16` (default)
`options.string-charset`	String tag encoding (Korean supported)	`MS949` (default)
`options.enable-iqr-extended`	Direct read of iQ-R extended devices (LCN/LZ/LF/LSTN/LCC/LSC)	`false` (default)

If controller-type is not specified, Q_L is used (Q / L series).

Tag `plc_address` Format

iot-communication notation. Device code + index (decimal) combination.

Notation	Meaning
`D100`	Data Register 100 (16-bit)
`D100.W`	16-bit word (explicit)
`D100.D`	32-bit double word (D100~D101)
`D100.F`	32-bit float (D100~D101)
`M100`	Internal relay 100 (1 bit)
`X100`	Input X100 (1 bit)
`Y100`	Output Y100 (1 bit)
`B0`	Link relay
`W100`	Link register
`R100`	File register

D Data Register, M Coil, X/Y I/O, R File Reg, W Link Reg.

`data_type` / `format` Mapping

`data_type`	`format`	Width / Interpretation
Boolean / Bool	(empty)	1-bit (M, X, Y, etc.)
Short / Int / Integer	(empty)	16-bit signed (W)
UInt16	`UI` / `UWORD`	16-bit unsigned
Int32 / DWord	`DW`	32-bit signed (2 words)
UInt32	`UDW`	32-bit unsigned
Float / REAL	`REAL`	32-bit IEEE 754
Double / LREAL	`LREAL`	64-bit IEEE 754
String	`STR[N]`	N words → 2N bytes ASCII

Batch mode (IS_BATCH_MODE=true) is enabled by default. All tags on a single PLC are bundled into one read request (REQUEST_LIMIT=1).

Common Errors and Fixes

Message / Symptom	Cause	Fix
Connection refused	MC protocol disabled, port blocked	Enable `MELSOFT 접속 / TCP / 포트 5000` in GX Works
`Wrong device code`	Unsupported device code	Verify `controller-type` match (device code differences between Q and iQ-R)
32-bit value mismatch	byte order	Specify `D100.D` (signed) / `D100.UD` (unsigned)
All tags read 0	network number / station number mismatch	Specify `network`, `station` in options (currently defaults to 0)

curl Registration Example

curl -X POST http://<edge-host>/api/v1/opc \
  -H "Content-Type: application/json" \
  -d '{
    "opc_id": "OPC_MELSEC_LINE1",
    "opc_type": "MELSEC",
    "opc_name": "Line1 Q-Series",
    "opc_agent_ip": "192.168.0.60",
    "opc_agent_port": "5000",
    "site_id": "SITE_00001",
    "auto_collect": true,
    "timecycle": 1000,
    "options": { "controller-type": "Q_L" },
    "tag_list": [
      {
        "tag_id": "OPC_MELSEC_LINE1_TAG_00001",
        "tag_name": "Counter",
        "plc_address": "D100",
        "data_type": "Integer"
      },
      {
        "tag_id": "OPC_MELSEC_LINE1_TAG_00002",
        "tag_name": "Pressure",
        "plc_address": "D200",
        "data_type": "Float",
        "format": "REAL"
      },
      {
        "tag_id": "OPC_MELSEC_LINE1_TAG_00003",
        "tag_name": "PumpRun",
        "plc_address": "M100",
        "data_type": "Boolean"
      }
    ]
  }'

Example Collection (by Data Type)

Mitsubishi device codes: D (Data), M (Internal Relay), X (Input), Y (Output), B (Link Relay), W (Link Register), R (File Register), T (Timer), C (Counter).

Bit / Boolean

`data_type`	`format`	`plc_address` example	Meaning
`Boolean`	(empty)	`M100`	Internal relay 100
`Boolean`	(empty)	`X100`	Input bit X100
`Boolean`	(empty)	`Y100`	Output bit Y100
`Boolean`	(empty)	`B0`	Link relay 0

16-bit Integer

`data_type`	`format`	`plc_address` example	Meaning
`Integer`	(empty)	`D100`	Data Register (signed 16)
`Integer`	(empty)	`D100.W`	Explicit 16-bit Word
`Integer`	`UI`	`D100`	unsigned 16
`Integer`	(empty)	`W100`	Link register
`Integer`	(empty)	`R100`	File register

32-bit Integer

`data_type`	`format`	`plc_address` example	Meaning
`Integer`	`DW`	`D100`	signed 32 (D100~D101 combined)
`Integer`	(empty)	`D100.D`	32-bit signed in library notation
`Integer`	`UDW`	`D100`	unsigned 32
`Integer`	(empty)	`D100.UD`	unsigned 32 in library notation

Floating Point

`data_type`	`format`	`plc_address` example	Meaning
`Float`	`REAL`	`D200`	IEEE 754 32-bit (D200~D201)
`Float`	(empty)	`D200.F`	Library notation
`Double`	`LREAL`	`D300`	IEEE 754 64-bit

String

`data_type`	`format`	`plc_address` example	Meaning
`String`	`STR[5]`	`D400`	5 words = 10 bytes ASCII
`String`	`STR[16]`	`D500`	16 words = 32 bytes

Using Formulas

Purpose	`data_type`	`fomula`	Notes
Integer raw → scaled real	`Float`	`${VALUE}*0.01`	12345 → 123.45
Counter accumulation (sum with another tag)	`Integer`	`${VALUE}+${TAG_PREV}`	Adds the previous accumulated value
Unit conversion (g → kg)	`Float`	`${VALUE}/1000`

Comprehensive curl Example

curl -X POST http://<edge-host>/api/v1/opc \
  -H "Content-Type: application/json" \
  -d '{
    "opc_id": "OPC_MELSEC_FULL",
    "opc_type": "MELSEC",
    "opc_name": "MELSEC iQ-R Full",
    "opc_agent_ip": "192.168.0.60",
    "opc_agent_port": "5000",
    "site_id": "SITE_00001",
    "auto_collect": true,
    "timecycle": 1000,
    "options": { "controller-type": "IQ_R" },
    "tag_list": [
      {"tag_id":"OPC_MELSEC_FULL_T01", "tag_name":"InternalBit", "plc_address":"M100", "data_type":"Boolean"},
      {"tag_id":"OPC_MELSEC_FULL_T02", "tag_name":"InputBit",    "plc_address":"X100", "data_type":"Boolean"},
      {"tag_id":"OPC_MELSEC_FULL_T03", "tag_name":"DataWord",    "plc_address":"D100", "data_type":"Integer"},
      {"tag_id":"OPC_MELSEC_FULL_T04", "tag_name":"DataDWord",   "plc_address":"D102", "data_type":"Integer", "format":"DW"},
      {"tag_id":"OPC_MELSEC_FULL_T05", "tag_name":"Pressure",    "plc_address":"D200", "data_type":"Float",   "format":"REAL"},
      {"tag_id":"OPC_MELSEC_FULL_T06", "tag_name":"Power",       "plc_address":"D300", "data_type":"Double",  "format":"LREAL"},
      {"tag_id":"OPC_MELSEC_FULL_T07", "tag_name":"Batch",       "plc_address":"D500", "data_type":"String",  "format":"STR[16]"},
      {"tag_id":"OPC_MELSEC_FULL_T08", "tag_name":"PressKpa",    "plc_address":"D200", "data_type":"Float",   "format":"REAL", "fomula":"${VALUE}*0.001"}
    ]
  }'

Overview​

OPC Registration Form​

Tag plc_address Format​

data_type / format Mapping​

Common Errors and Fixes​

curl Registration Example​

Example Collection (by Data Type)​

Bit / Boolean​

16-bit Integer​

32-bit Integer​

Floating Point​

String​

Using Formulas​

Comprehensive curl Example​