NL-43 / NL-53 Communication Guide (Concise Summary)

This is a terse operator/dev summary of the official “NL-43/NL-53 Communication Guide” (No. 66132, 97 pages). Use the PDF for authoritative details.

Transport Modes

USB CDC: Serial over USB. Mutually exclusive with LAN TCP/FTP/web/I/O port comm. No driver needed on Win10/11.
LAN (NX-43EX required): TCP control, FTP for file transfer, and optional web app (ports 80 and 8000). LAN TCP/FTP/web/USB comm are mutually exclusive—turning one on can disable the others.
RS-232C: Classic serial. Baud 9600–115200; DRD streaming requires ≥19200 (EX) or ≥57600 (RT).

ASCII text; end every command with CR LF.
Two types:
- Setting: $Command,Param[CR][LF]
- Request: Command?[CR][LF]
Wait for the leading $ prompt/idle before sending the next command; guide recommends ≥1 s between commands.
Result codes: R+0000 success; 0001 command error; 0002 parameter error; 0003 spec/type error; 0004 status error (wrong device state).
Control codes: CR=0x0D, LF=0x0A, SUB=0x1A (stop DRD stream).

Clock: Clock, YYYY/MM/DD hh:mm:ss | Clock?
Start/Stop: Measure, Start | Measure, Stop
Store mode: Store Mode, Manual|Auto (many related time/interval setters in Store section)
Manual store: Manual Store, Start
Battery/SD: Battery Level?, SD Card Total Size?, SD Card Free Size?, SD Card Percentage?
Display/Measure params: numerous Display ... and Measure ... setters/getters (frequency/time weighting, ranges, etc.).

Ethernet, On|Off — enable LAN.
Ethernet DHCP, On|Off — address assignment.
Ethernet IP|Subnet|Gateway, <value> — static settings.
TCP, On|Off — TCP control channel. TCP stops if USB comm, web app, or I/O port comm is turned on.
FTP, On|Off — file transfer mode (mutually exclusive with TCP/web/USB comm when active).
Web, On|Off — built-in web app (ports 80 and 8000). Disables Timer Auto, Trigger Mode, Delay Time, USB comm, LAN TCP, LAN FTP while in use.

DOD? — Snapshot of displayed values (Lp/Leq/LE/Lmax/Lmin/LN1–LN5/Lpeak/LIeq/Leq,mov/Ltm5 + over/under flags) for up to 4 channels. Leave ≥1 s between requests.
DLC? — Final calculation result set (similar fields as DOD) for last measurement/interval.
DRD? — Continuous output every 100 ms; stop by sending SUB (0x1A). Main/Sub1–Sub3 Lp/Leq/Lmax/Lmin/Lpeak/LIeq + over/under flags.
DRD?status — Same as DRD plus timestamp, power source (I/E/U), battery level (F/M/L/D/E), SD remaining MB, measurement state (M/S).
Optional NX-43RT variants include octave/1⁄3 octave band data appended.

Device responds within ~3 s; if busy, may return R+0004.
Time between sent characters: ≤100 ms.
After sending a command, wait for $ prompt/idle before the next; recommended 1 s.
DRD streaming continues until SUB (0x1A) is received.

Ports 80 and 8000; login required. Disables Timer Auto, Trigger Mode, Delay Time, I/O port comm, USB comm, LAN TCP, and LAN FTP while active.

NX-43EX: LAN TCP/FTP/web, DRD/DRD?status (EX flavor).
NX-43RT: Octave/1⁄3 octave features; DRD/DRD?status/DOD/DLC include band data; higher baud needed for RS-232C streaming.
NX-43WR: Waveform recording (noted in guide; specific settings in Operation Guide).

Install NX-43EX; on device: Ethernet On, set IP/subnet/gateway/DHCP; TCP, On; ensure USB comm + web app + I/O port comm are Off.
On controlling host/RX55: ensure port-forward/VPN to NL43 IP:TCP port (default 80).
Send Clock,<timestamp> to sync time.
Configure mode/intervals, then Measure, Start.
Poll DOD? for snapshots (≥1 s), or DRD?status for live stream; stop stream with SUB.
Switch to FTP, On only when pulling SD files; then back to TCP, On for control.