LDR series — three different protocols across one family
Transcribed from the manufacturer's own manuals · byte strings verified against the source PDF · no reverse-engineered guesses
LDR20K1 uses a 0x55 header with XOR checksum, LDR60K1/80K1 use 0xDD + ID 0x03 over RS-422, and LDR80K2 uses 0xEB 0x90 + length + command byte. Do not reuse one LDR driver for another.
Frame layout
输出帧 6 字节：0 Header 0xdd | 1 ID 0x03 | 2 Command Word 1 | 3 Command Word 2 | 4 Command Word 3 | 5 Checksum（bytes 0–4 求和 mod 256）；输入帧 8 字节：0 Header 0xdd | 1 ID 0x03 | 2 Status Word 1 | 3 Status Word 2 | 4 Distance / Count / Code period | 6 温度（二补码，°C）| 7 Checksum（bytes 0–6 求和 mod 256）。RS-422，115200 bps，1 起始位 / 8 数据位 / 1 停止位 / 无校验，LSB 先发，多字节低字节先发。
Command set
| Code | Function | Send | Reply | Notes / page |
|---|---|---|---|---|
0x00 | No self-test | Header 0xdd + ID 0x03 + CW1=0x00 + CW2 + CW3 + Checksum | 见输入帧 Table 7/8/9 | Command Word 1 取值（Table 4） |
0x01 | Self-test | Header 0xdd + ID 0x03 + CW1=0x01 + CW2 + CW3 + Checksum | 见输入帧 Table 7/8/9 | Command Word 1 取值（Table 4） |
0x10 | Single-shot ranging | Header 0xdd + ID 0x03 + CW1=0x10 + CW2 + CW3 + Checksum | 见输入帧 Table 7/8/9 | Command Word 1 取值（Table 4） |
0x02 | Ranging at 1 Hz | Header 0xdd + ID 0x03 + CW1=0x02 + CW2 + CW3 + Checksum | 见输入帧 Table 7/8/9 | Command Word 1 取值（Table 4） |
0x03 | Ranging at 5 Hz | Header 0xdd + ID 0x03 + CW1=0x03 + CW2 + CW3 + Checksum | 见输入帧 Table 7/8/9 | Command Word 1 取值（Table 4） |
0x04 | Single-burst designation (short-designation mode: laser on for 17 s pe | Header 0xdd + ID 0x03 + CW1=0x04 + CW2 + CW3 + Checksum | 见输入帧 Table 7/8/9 | Command Word 1 取值（Table 4） |
0x05 | Continuous-burst designation (long-designation mode: laser on for 47 s | Header 0xdd + ID 0x03 + CW1=0x05 + CW2 + CW3 + Checksum | 见输入帧 Table 7/8/9 | Command Word 1 取值（Table 4） |
0x06 | Short designation (one cycle, laser-on time configurable, < 60 s) | Header 0xdd + ID 0x03 + CW1=0x06 + CW2 + CW3 + Checksum | 见输入帧 Table 7/8/9 | Command Word 1 取值（Table 4） |
0x07 | Stop ranging / designation | Header 0xdd + ID 0x03 + CW1=0x07 + CW2 + CW3 + Checksum | 见输入帧 Table 7/8/9 | Command Word 1 取值（Table 4） |
0x08 | Range gating | Header 0xdd + ID 0x03 + CW1=0x08 + CW2 + CW3 + Checksum | 见输入帧 Table 7/8/9 | Command Word 1 取值（Table 4） |
0x09 | Read accumulated laser pulse count | Header 0xdd + ID 0x03 + CW1=0x09 + CW2 + CW3 + Checksum | 见输入帧 Table 7/8/9 | Command Word 1 取值（Table 4） |
0x11–0x20 | Code setting (codes 1–16) | Header 0xdd + ID 0x03 + CW1=0x11–0x20 + CW2 + CW3 + Checksum | 见输入帧 Table 7/8/9 | Command Word 1 取值（Table 4） |
0x21–0x30 | Code query (codes 1–16) | Header 0xdd + ID 0x03 + CW1=0x21–0x30 + CW2 + CW3 + Checksum | 见输入帧 Table 7/8/9 | Command Word 1 取值（Table 4） |
Timing and rates
p1 · The laser rangefinder/designator is equipped with an independent power-on control signal. By setting this p1 · 3. After 1 Hz ranging is started, if no stop command is received, the unit will automatically stop after 5 p1 · 4. After 5 Hz ranging is started, if no stop command is received, the unit will automatically stop after 5 p1 · 10. Supports self-test functions (including power-on self-test, periodic self-test, and start-up self-test) and p1 · a. Power-on self-test includes: p1 · b. Start-up and periodic self-test include: p2 · firing, the power-on self-test is not required to check these two fault types. During start-up and periodic p2 · Ranging rates: 1 Hz, 5 Hz, single-shot p2 · Continuous ranging operating time: 5 min(At 5 Hz: continuous operation for 5 min, rest time ≤ 3 min, p3 · Coding method: precise frequency code (eight groups of pre-stored period-code patterns).
Status codes and errors
p1 · outputs fault codes. p1 · High-temperature alarm. p1 · High-temperature alarm; p2 · firing, the power-on self-test is not required to check these two fault types. During start-up and periodic p2 · 12. Provides a temperature alarm output. p8 · 6.3.1 Status Bar Indication of Operating Status and Fault Display p8 · The status bar icons indicate the system’s operating and fault conditions: p8 · ” icon signifies a fault condition. p9 · If a red fault indicator appears, the current operation must be stopped immediately, and the fault should be p14 · Both parties shall strictly perform checksum validation. Any message with a failed checksum must be p16 · 1: Over-temperature p16 · alarm
What the source does not state
Where a manual prints an incomplete reply (for example only 55 for the
LD constant-on acknowledgement), this page reproduces that and stops — it does not pad the frame.
Anything not printed in the manual is absent here on purpose.
Models covered by this page
Source documents
- LDR20K1 · LDR20K1.pdf (12 pages)
- LDR60K1 · LDR60K1.pdf (15 pages)
- LDR80K1 · LDR80K1.pdf (17 pages)
- LDR80K2 · LDR80K2.pdf (25 pages)
Full transcription method: byte strings are asserted to exist in the extracted PDF text at build time, and re-checked against the page citation. If a string is not in the PDF, the page is not published.
Frequently asked questions
The same answers are published below as visible text and as FAQPage structured data, so the page and the markup cannot drift apart.
- What baud rate does the LDR20K1 family use?
- 115200 bps, 8 data bits, factory default; 9600 bps is selectable.
- How is the checksum computed?
- Command frames sum bytes 3–7; replies sum bytes 1–7, taking the low 8 bits. The manual states the two ranges separately.