Quick answer: ERDILRF 905 nm rangefinder modules ship in three wiring families. The H series uses a 5-pin 1.25 mm pigtail: red is 9–36 V in, black power ground, yellow port ground, green module TX, blue module RX. LRF22VB uses a 6-pin 0.8 mm pigtail in a different colour order. LR-E2, SPD and LRF3000A1 modules use a bare 6-pin header.
Most wiring guides stop at "connect TX to RX and share a ground". That is fine until two modules from the same catalogue sit on your bench and the green wire means two different things. This page is the physical layer only: pin order, wire colours, connector part numbers, and which electrical facts our source manuals do not publish. For the frame and checksum layer, see our UART-TTL integration guide and the serial protocol primer.
Family 1: the H series 5-pin pigtail
The industrial H series modules arrive pre-terminated: a 5-pin 1.25 mm terminal with 50 cm of tinned loose wire. All three share an identical colour map, so a harness built for one drops onto the others.
| Pin (wire colour) | LRF50H industrial module | LRF200H industrial module | LRF600H long-range module |
|---|---|---|---|
| 1 (red) | 9–36 V external power + | 9–36 V external power + | 9–36 V external power + |
| 2 (black) | Ground | External power − | External power − |
| 3 (yellow) | Ground | Port ground | Port ground |
| 4 (green) | Module TX → host RX | Module TX → host RX | Module TX → host RX |
| 5 (blue) | Module RX ← host TX | Module RX ← host TX | Module RX ← host TX |
| Terminal | M1250V-05P, 1.25 mm, 50 cm | 1.25 mm, 5-pin, 50 cm (no part number in manual) | 1.25 mm, 5-pin, 50 cm (no part number in manual) |
| Interface | UART only | UART, I²C | UART, I²C |
| Signal logic level | Not published | Not published | Not published |
Two details are worth pausing on. First, the H series gives you two grounds: a power return (black) and a port ground (yellow), separate pins because the 9–36 V rail and the signal pair reference ground independently — tie them at the host end, not mid-harness. Second, only LRF50H names a terminal you can order by part number; the LRF200H and LRF600H manuals give pitch and wire length but never name the housing, so match the 1.25 mm 5-pin family rather than assuming a brand.
Wire colours do not carry across families
This is the trap. LRF22VB, the 20 m short-range module, also ships pre-wired — a 6-pin 0.8 mm terminal (HC-0.8-6PWT) with 20 cm of tinned stranded wire — but its colours are laid out differently:
- Pin 1 white — not connected
- Pin 2 red — 3.3 V external power +
- Pin 3 yellow — TX / SCL
- Pin 4 green — RX / SDA
- Pin 5 blue — not connected
- Pin 6 black — external power −
Compare that against the table above. Red is still the positive rail and black is still the return, but green is the module’s transmit line on the H series and its receive line on LRF22VB; yellow is a ground on the H series and the transmit line on LRF22VB; and blue carries receive data on the H series while being unconnected on LRF22VB. Only two of six colours are portable. If you crimp a universal test harness for this catalogue, label it per family or you will swap TX and RX the first time you change models.
LRF22VB also shares pins 3 and 4 between UART and I²C — the manual names them "TX SCL" and "RXSDA" because the same physical pins serve both roles, and we keep that naming verbatim. Which modules expose a usable I²C path is covered in our I²C support survey.
Two more short-range modules ship pre-wired with published wire specifications but no colour table in our source documents: LRF50VB (4-pin 1.0 mm terminal, 10 cm) and LRF10VB (4-pin 1.25 mm terminal, 10 cm). We will not infer their colour order from siblings — a four-wire harness has no room for a guess. Ask for the pin drawing before you crimp.
Family 3: the bare 6-pin header
The LR-E2, SPD and A1 modules have no pigtail. You mate to a 6-pin header on the board, and the signal order is consistent across them:
| Pin | LR1200E2 module | SPD1200N0 cylindrical module | LRF3000A1 flagship module |
|---|---|---|---|
| 1 | GND | Power ground | Ground |
| 2 | VCC | Positive supply | 3.3–5 V DC supply |
| 3 | I/O, reserved | IO, reserved | NC, reserved |
| 4 | TXD (module → host) | TXD (module → host) | TTL_TXD, TTL 3.3 V level |
| 5 | RXD (host → module) | RXD (host → module) | TTL_RXD, TTL 3.3 V level |
| 6 | SW-SHOT, enable active HIGH | SW-SHOT, enable active HIGH | Enable — powers ON at LOW level |
| Pin 1→6 layout in drawing | In line, top to bottom | In line, side of cylindrical body | In a row, left to right |
| Connector part number | Not in manual (M1.4 screw spec only) | Not in manual | A1002WV-S-6P |
Three things bite people here. Pin 3 is reserved — leave it floating, not pressed into service as a second ground. Numbering orientation differs: LR-E2 drawings run pin 1 to 6 top to bottom, the LRF3000A1 socket drawing left to right, so "pin 1 is nearest the lens" is not a rule you can carry over. And enable polarity is inverted between the two groups: SW-SHOT on LR1200E2 and SPD1200N0 is active HIGH (the manual notes it can be built for an active-LOW requirement), whereas LRF3000A1 powers on when its enable pin is pulled LOW. One reused enable line across a mixed-model rig keeps one module asleep and the other awake.
Supply voltage is not signal voltage
The most expensive misreading in this catalogue is treating the supply rail as the logic level. The H series runs on 9–36 V DC because it is built for industrial cabinets — that says nothing about what its TX and RX pins swing to, and the manuals do not state it. Here is the honest status across the range:
- Published in the manual: LRF3000A1 — "Serial TX, TTL_3.3 V level" and "Serial RX, TTL_3.3 V level". SPD1200D03 also lists its interface as UART, TTL 3.3 V.
- Confirmed by the factory verbally, not yet in the manual: LR1000E2 at 3.3 V TX/RX, confirmed 14 September 2026, along with an 0.8 mm-pitch 6P mating connector and a pre-terminated pigtail supplied with samples. The connector brand and part number are still outstanding.
- Not published: LR1200E2, LR2000E2, SPD1200N0, LRF50H, LRF200H and LRF600H. These are logged as open gaps in our internal specification register, and we quote them as unknown rather than extrapolating from the supply range.
Practically: wiring an unpublished module to a 3.3 V microcontroller means budgeting for a level shifter and requesting written confirmation before you commit a production harness. For autopilot work, the ArduPilot rangefinder documentation covers the serial port side of the same job. Every module here is IEC 60825-1 Class 1 as supplied.
Frequently asked questions
Which wire is TX on an ERDILRF rangefinder module?
Green on the H series (LRF50H, LRF200H, LRF600H), where green is the module’s output into your host’s RX pin. Yellow on LRF22VB, where green is instead the receive line. On the header-based modules there are no wires at all: TXD is pin 4.
Can I plug a 9–36 V module’s serial pins straight into a 3.3 V MCU?
Not on an assumption. The H series manuals publish the 9–36 V supply range but never state the TX/RX logic level, so the safe path is a level shifter plus written confirmation from us. Only LRF3000A1 and SPD1200D03 state TTL 3.3 V signalling in their own documentation.
What mating connector do I order?
M1250V-05P for LRF50H, HC-0.8-6PWT for LRF22VB, and A1002WV-S-6P for LRF3000A1. LRF200H and LRF600H specify a 1.25 mm 5-pin terminal with 50 cm leads but no part number; the LR-E2 and SPD1200N0 manuals give only an M1.4 mounting screw spec.
Does the enable pin have to be driven?
Pin 6 exists on every header-family module, but the polarity is not uniform: active HIGH on LR1200E2 and SPD1200N0, active LOW on LRF3000A1. Confirm the polarity for your specific model before you tie it to a GPIO.
Need a pin drawing, a mating connector part number, or written confirmation of a logic level? Tell us the model and your host voltage — we will send what the manual states and say plainly where it is silent.