device library

Siemens OpenAir GDB/GLB181.1E/MO VAV compact controller

Register map(s) for this device, with a note of how far each has been checked. Addresses are 0-based, as on the wire. Scale and byte order are confirmed only at the hardware-verified rung.

coherence-checked

Round-trips through a real Modbus stack with no overlapping addresses and a word-order-sensitive codec — the map is internally coherent and wire-decodable. Does NOT prove byte-order or scaling match a real device: the emulator is seeded from the map's own types, so a uniformly wrong byte-order still round-trips. Only hardware-verified confirms byte-order/scale on the wire.

pointaddress (0-based)typescaleunit
setpoint0U160.01%
override_control1U161
actual_position2U160.01%
actual_flow_rel3U160.01%
actual_flow_abs4U161m3/h
actual_pressure5U160.1Pa
command255U161
opening_direction256U161
adaptive_mode257U161
operating_mode258U161
min_position259U160.01%
max_position260U160.01%
actuator_running_time261U161s
vnom384U161m3/h
vmin385I160.01%
vmax386U160.01%
altitude_level387U161m
unit_switch388U161
backup_mode512U161
backup_position513U160.01%
backup_timeout514U161s
modbus_address763U161
baudrate764U161
transmission_format765U161
bus_termination766U161
bus_conf_command767U161
status768U161

link settings as documented (unverified): RTU; baud 9600/19200/38400/57600/76800/115200; unit ID 255; FC 03,04,06,16; Default baud rate is Auto. Default transmission format is 1-8-E-1. Maximum of 120 registers within one message.

bench facts as documented (unverified)
terminalsTerminal strip 7-pin, grid 2.00 mm
A/B polarityBus + on grey (GY), Bus - on pink (PK), REF on violet (VT)
termination120 Ohm electronically switchable
connectorPrewired cables (power / communication)
isolationgalvanically separated
wiring notesDelivered with two prewired cables.
max registers/read120
protocol notesOverwriting the bus configuration over bus uses a timeout. If '1 = Load' is not written into Reg 768 within 30 seconds, all values are discarded.
model register1408
serial register1283
powerAC 24 V ± 20 % (SELV) or AC 24 V class 2 (US), 50/60 Hz, 1 VA / 0.5 W (holding), 3 VA / 2.5 W (rotating)
environmentClass 3K5, Indoors, 0...50 °C, 5...95 % r. F. (non condensing)
accuracyDifferential pressure sensor: Zero point ± 0.2 Pa, Amplitude ± 4.5 % of the measured value, Drift ± 0.1 Pa / Year
certificationsCE, RCM, UL, cUL
doc revisionA6V10631832_en--_d (2018-04-16)
field reports — community-sourced, unverified (checked 2026-06-11)
  • confirmed: Baud rates [9600, 19200, 38400, 57600, 76800, 115200] and default transmission format 1-8-E-1 — confirmed by Siemens Technical Basics VAV Modbus (A6V10631862)
  • confirmed: Differential pressure sensor accuracy (Zero point ± 0.2 Pa, Amplitude ± 4.5 %, Drift ± 0.1 Pa / Year) — confirmed by Siemens G..B181..MO Datasheet (A6V10631832)
  • confirmed: Bus polarity (Bus + on grey GY, Bus - on pink PK, REF on violet VT) — confirmed by Siemens G..B181..MO Datasheet (A6V10631832)
  • confirmed: Modbus register map (0-based setpoint @ 0, override_control @ 1, actual_position @ 2, actual_flow_rel @ 3, actual_flow_abs @ 4, actual_pressure @ 5, command @ 255, opening_direction @ 256, adaptive_mode @ 257, operating_mode @ 258, min_position @ 259, max_position @ 260, actuator_running_time @ 261, vnom @ 384, vmin @ 385, vmax @ 386, altitude_level @ 387, unit_switch @ 388, backup_mode @ 512, backup_position @ 513, backup_timeout @ 514, modbus_address @ 763, baudrate @ 764, transmission_format @ 765, bus_termination @ 766, bus_conf_command @ 767, status @ 768) — confirmed by Siemens Technical Basics VAV Modbus (A6V10631862)
  • confirmed: Bus configuration timeout quirk (If '1 = Load' is not written into Reg 768 within 30 seconds, all values are discarded) — confirmed by Siemens G..B181..MO Datasheet (A6V10631832)

The trust ladder

Each rung states what it proved and what it did not. Gray until proven; green is earned by hardware only.

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