An unofficial summary of facts (addresses, types, units, scaling) from the maker's manual. Not affiliated with the maker; values can differ by firmware or model. Always check the device manual before writing (run commands, settings).
Default communication
| Protocol | Modbus RTU |
|---|---|
| Baud (factory) | 9600 bps — options: 2400, 4800, 9600, 19200, 38400 |
| Data · parity · stop | — · None · 1 |
| Slave ID (factory) | 1 (1~127) |
| Manual address style | 40001/30001 style (wire address + 1, first digit = table) |
- Evidence: the manual writes '40001 (0000)' = PLC number plus hex wire address. Printed p.32 (PDF p.31): FC01 example '01 01 00 00 00 03 7C 0B' reads coils 00001-00003 (0000-0002, L/GO/H-OUT); FC02 example '01 02 00 00 00 01 B9 CA' reads 10001 (0000, HOLD). Printed p.34 (PDF p.33): exception example '01 03 00 95 00 07' starts at the unused address just before 40151 (0096) and gets exception 02. Wire address = bracket value = PLC number minus 00001/10001/30001/40001. All example CRCs verified.
- Defaults: station 001, 9600 bps, parity NONE, response wait 20 ms, comm write protect ON (printed p.27, PDF p.26). Stop bit fixed at 1 (40154 '0 (1-STOP)' fixed, printed p.39). Data bits are not stated in the manual.
- With write protect (CWP) ON, write requests get exception 04 (printed p.34) — set CWP OFF first.
Registers (46)
«Wire» is the 0-based address in the request frame (PortDock's «0-based» notation). Value = raw × scale. Table: HR holding register, IR input register, CO coil, DI discrete input. Function codes in hex.
46
Swipe the table sideways — the first column (manual address) stays put.
| Manual | Wire | Table | Name | Type | Unit · scale | R/W | FC | Details |
|---|---|---|---|---|---|---|---|---|
| 00001 (0000) | 0 (0x0000) | CO | LOW-OUT output state | BIT | R | 01 | 0 = OFF · 1 = ON printed p.35 (PDF p.34) | |
| 00002 (0001) | 1 (0x0001) | CO | GO-OUT output state | BIT | R | 01 | 0 = OFF · 1 = ON printed p.35 (PDF p.34) | |
| 00003 (0002) | 2 (0x0002) | CO | HIGH-OUT output state | BIT | R | 01 | 0 = OFF · 1 = ON printed p.35 (PDF p.34) | |
| 10001 (0000) | 0 (0x0000) | DI | HOLD input state | BIT | R | 02 | 0 = OFF · 1 = ON printed p.35 (PDF p.34) | |
| 30101 (0064) | 100 (0x0064) | IR | Product number (low word) | U16 | R | 04 | printed p.35 (PDF p.34) | |
| 30102 (0065) | 101 (0x0065) | IR | Product number (high word) | U16 | R | 04 | printed p.35 (PDF p.34) | |
| 30103 (0066) | 102 (0x0066) | IR | Hardware version | U16 | R | 04 | printed p.35 (PDF p.34) | |
| 30104 (0067) | 103 (0x0067) | IR | Firmware version | U16 | R | 04 | printed p.35 (PDF p.34) | |
| 30105 (0068) | 104 (0x0068) | IR | Model name | STRING(2) | R | 04 | Two characters "LM". printed p.35 (PDF p.34) | |
| 30106 (0069) | 105 (0x0069) | IR | Measuring input type | STRING(2) | R | 04 | "AV" AC voltage, "AA" AC current, "DV" DC voltage, "DA" DC current. printed p.35 (PDF p.34) | |
| 30107 (006A) | 106 (0x006A) | IR | Option output type | U16 | R | 04 | 0 = N (indicator only) · 3 = RC (1-stage output) · 5 = 3RC/3NC/3PC (3-stage output) b0 0 indicator only / 1 with output · b1 1-stage · b2 3-stage printed p.35 (PDF p.34) | |
| 31001 (03E8) | 1000 (0x03E8) | IR | Active lamp status | U16 | R | 04 | b1 L-OUT lamp · b2 GO-OUT lamp · b3 H-OUT lamp · b4 DC lamp · b5 AC lamp · b6 L-SET lamp · b7 H-SET lamp · b8 COM lamp · b9 RMS lamp · b10 CWP lamp · b11 LOCK lamp · b12 ZERO lamp · b13 HOLD lamp · b14 MIN lamp · b15 MAX lamp printed p.36 (PDF p.35) | |
| 31002 (03E9) | 1001 (0x03E9) | IR | Unit lamp status | U16 | R | 04 | mV sets bit1+bit2, mA sets bit3+bit4, KW sets bit5+bit6. b1 V lamp · b2 mV lamp · b3 A lamp · b4 mA lamp · b5 W lamp · b6 KW lamp · b7 Hz lamp printed p.36 (PDF p.35) | |
| 31003 (03EA) | 1002 (0x03EA) | IR | Process value (PV) | S16 | R | 04 | Raw -9999..9999. Decimal point follows DOT (e.g. DOT=1: raw 1234 = 123.4). 9999 on OVER/S.OVR, -9999 on -OVER/-S.OVR. printed p.36 (PDF p.35) | |
| 31004 (03EB) | 1003 (0x03EB) | IR | Maximum value (MAX) | S16 | R | 04 | Decimal point follows DOT (e.g. DOT=1: raw 1234 = 123.4). printed p.36 (PDF p.35) | |
| 31005 (03EC) | 1004 (0x03EC) | IR | Minimum value (MIN) | S16 | R | 04 | Decimal point follows DOT (e.g. DOT=1: raw 1234 = 123.4). printed p.36 (PDF p.35) | |
| 31006 (03ED) | 1005 (0x03ED) | IR | Low comparison value (LSV) | S16 | R | 04 | Decimal point follows DOT (e.g. DOT=1: raw 1234 = 123.4). printed p.36 (PDF p.35) | |
| 31007 (03EE) | 1006 (0x03EE) | IR | High comparison value (HSV) | S16 | R | 04 | Decimal point follows DOT (e.g. DOT=1: raw 1234 = 123.4). printed p.36 (PDF p.35) | |
| 31008 (03EF) | 1007 (0x03EF) | IR | Decimal point (DOT) | U16 | R | 04 | 0 = 0000 · 1 = 000.0 · 2 = 00.00 · 3 = 0.000 printed p.36 (PDF p.35) | |
| 31009 (03F0) | 1008 (0x03F0) | IR | Input range (RANG) | U16 | R | 04 | Range depends on model: AV 0-7, AA 0-5, DV 0-7, DA 0-7. 0 = AV 500V, AA 5A, DV 500V, DA 5A · 1 = AV 250V, AA 2A, DV 100V, DA 2A · 2 = AV 110V, AA 500mA, DV 50V, DA 500mA · 3 = AV 50V, AA 200mA, DV 10V, DA 200mA · 4 = AV 20V, AA 50mA, DV 5V, DA 50mA · 5 = AV 10V, AA 20mA, DV 1V, DA 4-20mA · 6 = AV 2V, DV 200mV, DA 5mA · 7 = AV 1V, DV 50mV, DA 2mA printed p.37 (PDF p.36) | |
| 31010 (03F1) | 1009 (0x03F1) | IR | Output mode (O-MD) | U16 | R | 04 | Output models only. 0 = Output OFF · 1 = LO output mode · 2 = HI output mode · 3 = LH output mode · 4 = LL output mode · 5 = HH output mode · 6 = LD output mode printed p.37 (PDF p.36) | |
| 40001 (0000) | 0 (0x0000) | HR | Low comparison value (LSV) | S16 | R/W | 03·06·10 | Set LSV < HSV. Used in LD/LO/HH/LL/LH output modes. Decimal point follows DOT (e.g. DOT=1: raw 1234 = 123.4). printed p.37 (PDF p.36) | |
| 40002 (0001) | 1 (0x0001) | HR | High comparison value (HSV) | S16 | R/W | 03·06·10 | Set HSV > LSV. Used in HI/HH/LL/LH output modes. Decimal point follows DOT (e.g. DOT=1: raw 1234 = 123.4). printed p.37 (PDF p.36) | |
| 40051 (0032) | 50 (0x0032) | HR | Measuring mode (FUNC) | U16 | R/W | 03·06·10 | FREQ on AV/AA models only. 0 = Normal (NOR) · 1 = Scaled (SCAL) · 2 = Frequency (FREQ) printed p.38 (PDF p.37) | |
| 40052 (0033) | 51 (0x0033) | HR | Input range (RANG) | U16 | R/W | 03·06·10 | Range depends on model: AV 0-7, AA 0-5, DV 0-7, DA 0-7. 0 = AV 500V, AA 5A, DV 500V, DA 5A · 1 = AV 250V, AA 2A, DV 100V, DA 2A · 2 = AV 110V, AA 500mA, DV 50V, DA 500mA · 3 = AV 50V, AA 200mA, DV 10V, DA 200mA · 4 = AV 20V, AA 50mA, DV 5V, DA 50mA · 5 = AV 10V, AA 20mA, DV 1V, DA 4-20mA · 6 = AV 2V, DV 200mV, DA 5mA · 7 = AV 1V, DV 50mV, DA 2mA printed p.38 (PDF p.37) | |
| 40054 (0035) | 53 (0x0035) | HR | Zero offset correction (ZERO) | S16 | R/W | 03·06·10 | Range -99 ~ 99 printed p.38 (PDF p.37) | |
| 40056 (0037) | 55 (0x0037) | HR | AC measuring method (AC.TY) | U16 | R/W | 03·06·10 | AV/AA models only. 0 = Average · 1 = True RMS printed p.38 (PDF p.37) | |
| 40057 (0038) | 56 (0x0038) | HR | Display period (D.REF) | U16 | R/W | 03·06·10 | 0 = 100 ms · 1 = 200 ms · 2 = 500 ms · 3 = 1 s · 4 = 2 s · 5 = 5 s printed p.38 (PDF p.37) | |
| 40058 (0039) | 57 (0x0039) | HR | Detection delay (D.TMR) | U16 | s | R/W | 03·06·10 | 0 disables MAX/MIN display. Range 0 ~ 99 s printed p.38 (PDF p.37) |
| 40059 (003A) | 58 (0x003A) | HR | External input function (EX.IN) | U16 | R/W | 03·06·10 | 0 = HOLD · 1 = ZERO printed p.38 (PDF p.37) | |
| 40060 (003B) | 59 (0x003B) | HR | Front-key zero adjust (K-ZO) | U16 | R/W | 03·06·10 | 0 = OFF · 1 = ON printed p.38 (PDF p.37) | |
| 40061 (003C) | 60 (0x003C) | HR | Lock (LOCK) | U16 | R/W | 03·06·10 | 0 = Unlocked · 1 = Front keys (KEY) · 2 = All parameters (PAR) · 3 = Keys and all parameters (K-P) · 4 = Output parameters (OUT) · 5 = Transmission/comm parameters (OPT) printed p.38 (PDF p.37) | |
| 40062 (003D) | 61 (0x003D) | HR | Decimal point (DOT) | U16 | R/W | 03·06·10 | In SCALE or FREQ mode. 0 = 0000 · 1 = 000.0 · 2 = 00.00 · 3 = 0.000 printed p.38 (PDF p.37) | |
| 40063 (003E) | 62 (0x003E) | HR | Prescale high (SC-H) | S16 | R/W | 03·06·10 | SCALE mode only. Raw integer. Range -9999 ~ 9999 printed p.38 (PDF p.37) | |
| 40064 (003F) | 63 (0x003F) | HR | Prescale low (SC-L) | S16 | R/W | 03·06·10 | SCALE mode only. Raw integer. Range -9999 ~ 9999 printed p.38 (PDF p.37) | |
| 40065 (0040) | 64 (0x0040) | HR | Unit display (UNIT) | U16 | R/W | 03·06·10 | 0 = Unit of selected range · 1 = All unit lamps OFF · 2 = V · 3 = mV · 4 = A · 5 = mA · 6 = W · 7 = KW · 8 = HZ printed p.38 (PDF p.37) | |
| 40066 (0041) | 65 (0x0041) | HR | Range display (D.RNG) | U16 | R/W | 03·06·10 | 0 = OFF · 1 = ON printed p.38 (PDF p.37) | |
| 40101 (0064) | 100 (0x0064) | HR | Output mode (O-MD) | U16 | R/W | 03·06·10 | Output models only. 0 = Output OFF · 1 = LO output mode · 2 = HI output mode · 3 = LH output mode · 4 = LL output mode · 5 = HH output mode · 6 = LD output mode printed p.39 (PDF p.38) | |
| 40103 (0066) | 102 (0x0066) | HR | Hysteresis (HYS) | U16 | R/W | 03·06·10 | Up to 10 % of max display. Ignored when output mode is OFF. Range 0 ~ 999 printed p.39 (PDF p.38) | |
| 40104 (0067) | 103 (0x0067) | HR | Retransmission scale high (PV.SH) | S16 | R/W | 03·06·10 | Retransmission (4-20 mA) models only. PV.SH > PV.SL. Decimal point follows DOT (e.g. DOT=1: raw 1234 = 123.4). printed p.39 (PDF p.38) | |
| 40105 (0068) | 104 (0x0068) | HR | Retransmission scale low (PV.SL) | S16 | R/W | 03·06·10 | Retransmission (4-20 mA) models only. PV.SL < PV.SH. Decimal point follows DOT (e.g. DOT=1: raw 1234 = 123.4). printed p.39 (PDF p.38) | |
| 40151 (0096) | 150 (0x0096) | HR | Station number (S-NO) | U16 | R/W | 03·06·10 | Range 1 ~ 127 printed p.39 (PDF p.38) | |
| 40152 (0097) | 151 (0x0097) | HR | Baud rate (BPS) | U16 | R/W | 03·06·10 | 0 = 2400 · 1 = 4800 · 2 = 9600 · 3 = 19200 · 4 = 38400 printed p.39 (PDF p.38) | |
| 40153 (0098) | 152 (0x0098) | HR | Parity (PTY) | U16 | R/W | 03·06·10 | 0 = NONE · 1 = ODD · 2 = EVEN printed p.39 (PDF p.38) | |
| 40155 (009A) | 154 (0x009A) | HR | Response wait time (RWT) | U16 | ms | R/W | 03·06·10 | Range 5 ~ 99 ms printed p.39 (PDF p.38) |
| 40156 (009B) | 155 (0x009B) | HR | Communication write protect (CWP) | U16 | R/W | 03·06·10 | 0 = OFF · 255 = ON (FFh) printed p.39 (PDF p.38) |
Notes
- Communication is optional — only option code 'C' models (LM3-...-3RC/3NC/3PC-A, LM6-...-RC-A) have RS485 (printed p.6, PDF p.5).
- PV, MAX, MIN, comparison values and retransmission scales are integers without decimal point; DOT (31008/40062) sets the decimal position.
- SPAN (40053, 0.100-5.000), FACT (40055), S.TMR (40102, 0.0-99.9 s) and stop bit (40154) are omitted: raw encoding not stated or fixed.
- The register map is only in the Korean user manual (2023); the 2-page English manual (LM_manual_en_260224) has none. This source covers LM3 and LM6 only.
Read it with PortDock
- Install the free PortDock Modbus Master and connect with the device's settings.
- On the table toolbar, «Device profile…» → pick this device → «Load». Polling tables, names, types and the Slave ID are filled in (optionally the serial settings too).
- Names carry the unit and scale (e.g. «×0.01 Hz»). Values on screen are raw — multiply by the scale.
- To test your program without the device, PortDock Modbus Slave's «Emulate device…» serves the same map with example values.
Download JSON
- hanyoung-nux/lm.json (GitHub raw) · copy on this site · history
- schema.json — format (JSON Schema). table, address (0-based), type and order match the PortDock CSV.
- License: CC BY 4.0 — please cite:
PortDock device register maps, v2026.10 · 09ac1d0b2792, https://portdock.dev/devices/
and this page. LICENSE · data bundle, version and changelog - Found a mistake? Please open a GitHub issue with the manual page.
Sources
- LM SERIES LCD 디스플레이 멀티패널미터 — Hanyoung Nux, MF0601K230627_U (PDF created 2023-06-28, file LM_user_kr) · printed p.6 ordering, p.8 specs, p.27 comm defaults, pp.31-34 protocol and frame examples, pp.35-39 map (PDF page = printed page - 1) · checked 2026-10-23