Supported registers

This page lists the public device families and address forms accepted by the Node-RED high-level nodes.

Bit device families

Family	Example	Numbering	Notes
`SM`	`SM400`	Decimal	Special relay.
`X`	`X20`	Octal on `melsec:iq-f`, hexadecimal on other profiles	Input.
`Y`	`Y20`	Octal on `melsec:iq-f`, hexadecimal on other profiles	Output.
`M`	`M1000`	Decimal	Internal relay.
`L`	`L100`	Decimal	Latch relay.
`F`	`F10`	Decimal	Annunciator.
`V`	`V10`	Decimal	Edge relay where supported. Not valid for `melsec:iq-f`.
`B`	`B20`	Hexadecimal	Link relay.
`TS`	`TS10`	Decimal	Timer contact.
`TC`	`TC10`	Decimal	Timer coil.
`LTS`	`LTS10`	Decimal	Long timer contact where supported.
`LTC`	`LTC10`	Decimal	Long timer coil where supported.
`STS`	`STS10`	Decimal	Retentive timer contact.
`STC`	`STC10`	Decimal	Retentive timer coil.
`LSTS`	`LSTS10`	Decimal	Long retentive timer contact where supported.
`LSTC`	`LSTC10`	Decimal	Long retentive timer coil where supported.
`CS`	`CS10`	Decimal	Counter contact.
`CC`	`CC10`	Decimal	Counter coil.
`LCS`	`LCS10`	Decimal	Long counter contact where supported.
`LCC`	`LCC10`	Decimal	Long counter coil where supported.
`SB`	`SB20`	Hexadecimal	Link special relay.
`DX`	`DX20`	Hexadecimal	Direct input. Not valid for `melsec:iq-f`.
`DY`	`DY20`	Hexadecimal	Direct output. Not valid for `melsec:iq-f`.

Family	Example	Numbering	Notes
`SD`	`SD100`	Decimal	Special register.
`D`	`D100`	Decimal	Data register. Recommended for the first read.
`W`	`W20`	Hexadecimal	Link register.
`TN`	`TN10`	Decimal	Timer current value.
`LTN`	`LTN10:D`	Decimal	Long timer current value where supported. Use `:D` or `:L`.
`STN`	`STN10`	Decimal	Retentive timer current value.
`LSTN`	`LSTN10:D`	Decimal	Long retentive timer current value where supported. Use `:D` or `:L`.
`CN`	`CN10`	Decimal	Counter current value.
`LCN`	`LCN10:D`	Decimal	Long counter current value where supported. Use `:D` or `:L`.
`SW`	`SW20`	Hexadecimal	Link special register.
`Z`	`Z10`	Decimal	Index register.
`LZ`	`LZ0:D`	Decimal	Long index register where supported. Use `:D` or `:L`.
`R`	`R100`	Decimal	File register where supported.
`ZR`	`ZR100`	Decimal	Extended file register where supported. Not valid for `melsec:iq-f`.
`RD`	`RD100`	Decimal	Refresh data register where supported. Not valid for `melsec:iq-f`, `melsec:qcpu`, `melsec:lcpu`, `melsec:qnu`, or `melsec:qnudv`.

Form	Example	Meaning
Plain word	`D100`	Unsigned 16-bit word.
Signed word	`D100:S`	Signed 16-bit word.
Signed word alias	`D100:I`	Alias that normalizes to `D100:S`.
Unsigned dword	`D100:D`	Unsigned 32-bit value.
Signed dword	`D100:L`	Signed 32-bit value.
Float	`D100:F`	32-bit float.
String	`D100:STR,10`	UTF-8 string with a 10-byte maximum, packed two bytes per word.
String alias	`DSTR100,10`	Compatibility alias for `D100:STR,10`.
Bit in word	`D50.3`	One bit inside a word device.
Counted word	`D100,4`	Four consecutive word values.
Direct bit	`M1000`	One bit device.
Counted bit	`M1000,8`	Eight consecutive bit values.

LTN, LSTN, LCN, and LZ are 32-bit families. Use :D or :L, for example LTN0:D or LCN0:L.
G and HG are not in the public node surface.
DX and DY are not valid for melsec:iq-f.
X and Y numbering is octal for melsec:iq-f and hexadecimal for all other profiles.
.bit notation is only valid on word devices, for example D50.3.
.bit,count is not supported.
String forms require a length, for example D100:STR,10.
The editor validates address format and PLC-profile support. It does not validate your PLC model's configured upper address range.

See PLC profiles for the exact canonical profiles, frame mapping, and profile-specific cautions.