Connect Mitsubishi MELSEC

Proxus supports native communication with Mitsubishi MELSEC controllers via the MC (MELSEC Communication) protocol and Computer Link variants.

Supported Models & Protocol Types

Select the correct ProtocolType matching your hardware and connection method:

Protocol Type	Hardware Series	Connection	Notes
`Mitsubishi_MelsecMc`	Q, L, R Series	Ethernet	Standard binary MC protocol (3E/4E frame)
`Mitsubishi_MelsecMcAscii`	Q, L, R Series	Ethernet	ASCII MC protocol
`Mitsubishi_MelsecA1E`	A Series	Ethernet	Legacy A-Series Ethernet
`Mitsubishi_MelsecFxSerial_OverTcp`	FX Series	Serial/Ethernet	FX Computer Link (Programming Port)
`Mitsubishi_MelsecFxLinks_OverTcp`	FX3U, FX5U	Serial/Ethernet	Computer Link protocol
`Mitsubishi_MelsecA3C_OverTcp`	A, QnA	Serial/Ethernet	A3C Protocol

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Recommended Setting

For modern Q, L, and R series controllers with Ethernet ports, use Mitsubishi_MelsecMc. It provides the best performance.

Connection Parameters

Basic Settings

Parameter	Type	Required	Default	Description
Host	string	Yes	-	PLC IP Address
Port	int	No	-	Port (see defaults below)
PollingInterval	int	No	`1000`	Read cycle interval in milliseconds
ConnectTimeout	int	No	`3000`	Connection timeout (ms)
ReceiveTimeout	int	No	`3000`	Response timeout (ms)

Protocol-Specific Settings

Depending on the ProtocolType, additional parameters may be available:

MC Protocol (Q, L, R Series)

Applies to Mitsubishi_MelsecMc, Mitsubishi_MelsecMcAscii, Mitsubishi_MelsecMcR

Parameter	Type	Default	Description
NetworkNumber	byte	`0`	MELSECNET network number
NetworkStationNumber	byte	`0`	Station number within the network
EnableWriteBitToWordRegister	bool	`false`	Allow writing bits to word registers

FX Series & Computer Link

Applies to Mitsubishi_MelsecFxLinks_OverTcp, Mitsubishi_MelsecA3C_OverTcp

Parameter	Type	Default	Description
Station	byte	`0`	Station/Unit ID
Format	int	`1`	Computer Link format (1-4)
SumCheck	bool	`true`	Enable checksum validation
WaittingTime	byte	`0`	Response delay (0-15, FX Links only)

FX Serial (Programming Port)

Applies to Mitsubishi_MelsecFxSerial_OverTcp

Parameter	Type	Default	Description
isNewVersion	bool	`false`	Set to `true` for newer FX series (e.g. FX3U)
UseGot	bool	`false`	Enable when connecting through a GOT HMI passthrough

Legacy A-Series (A1E)

Applies to Mitsubishi_MelsecA1E, Mitsubishi_MelsecA1EAscii

Parameter	Type	Default	Description
PlcNumber	byte	`255`	PLC Number (typically 255 for local)

Default Ports

Protocol	Default Port
MC Protocol (Binary/ASCII)	`6000`
FX Computer Link	`485`
Ethernet/IP (CIP)	`44818`

Address Syntax

Proxus supports the standard Mitsubishi device notation. Addresses are case-insensitive.

Common Memory Areas

Device	Prefix	Description	Example
Input	`X`	Digital Input (Hexadecimal)	`X10`, `X1F`
Output	`Y`	Digital Output (Hexadecimal)	`Y10`, `Y20`
Internal Relay	`M`	Internal Bit	`M100`, `M2000`
Latch Relay	`L`	Latched (Retentive) Bit	`L100`
Link Relay	`B`	Link Bit (Hexadecimal)	`B100`, `B1A`
Data Register	`D`	16-bit Data Register	`D100`, `D200`
Link Register	`W`	16-bit Link Register (Hex)	`W100`, `W1A`
Timer Contact	`TS`	Timer Status (Bit)	`TS100`
Timer Current	`TN`	Timer Value (Word)	`TN100`
Counter Contact	`CS`	Counter Status (Bit)	`CS100`
Counter Current	`CN`	Counter Value (Word)	`CN100`
File Register	`R` / `ZR`	Extended Memory	`R100`, `ZR1000`

Hexadecimal Addressing

Important: Inputs (X), Outputs (Y), Link Relays (B), and Link Registers (W) use hexadecimal addressing.

X10 is index 16 (decimal)
X0F is index 15 (decimal)
W10 is index 16 (decimal)

All other areas (M, D, TN, CN, etc.) use decimal addressing.

Data Types

Proxus Type	Mitsubishi Equivalent	Size	Notes
Bool	Bit	1 bit	M, X, Y, L, B, etc.
Short	Word (Signed)	16 bit	D, W, R, etc.
UShort	Word (Unsigned)	16 bit
Int	Double Word (Signed)	32 bit	Uses 2 consecutive registers
UInt	Double Word (Unsigned)	32 bit	Uses 2 consecutive registers
Float	Real	32 bit	Uses 2 consecutive registers
Double	Double Real	64 bit	Uses 4 consecutive registers
String	String	Variable	ASCII string

PLC Configuration (MC Protocol)

To connect using Mitsubishi_MelsecMc, you must configure the Ethernet module in GX Works2 or GX Works3:

Go to Network Parameter -> Ethernet / CC-Link IE Field.
Select Open Settings.
Add a new connection:
- Protocol: TCP
- Open System: MC Protocol
- Host Station Port No: (e.g., 6000)
Write parameters to PLC and power cycle.

Troubleshooting

Error	Cause	Solution
Connection Refused	Wrong IP or Port	Verify IP and Port settings
Timeout	PLC Busy or Network Issue	Increase `ConnectTimeout` / Check firewall
Read Error	Invalid Address	Check if address exists (e.g. `W` vs `D`)
Access Denied	PC Parameter setting	Check "Open Settings" in PLC Parameters
Timeout	Network or Firewall	Verify port 5000/5002 is open

Official Resources

Mitsubishi Electric Global: FA Download Center (Manuals)
e-Manual Viewer: MELSEC e-Manual Viewer