GF Signet 9900 transmitter

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.

point	address (0-based)	type	scale
status	0	U32BE	1
primary_reading	2	F32BE	1
secondary_reading	4	F32BE	1
measurement_type	6	U16	1
primary_units_of_measure_code	7	U16	1
secondary_units_of_measure_code	8	U16	1
modbus_address	9000	U16	1
network_termination	9001	U16	1
modbus_mode	9002	U16	1
baud_rate	9003	U16	1
parity	9004	U16	1
floating_point_endian	9005	U16	1
save_reboot	9006	U16	1
hsb_transactions	9103	U16	1
second_counter	9104	U16	1
bus_message_counter	9105	U16	1
bus_message_error_counter	9106	U16	1
slave_exception_counter	9107	U16	1
slave_message_counter	9108	U16	1
slave_no_response_counter	9109	U16	1
slave_nak_counter	9110	U16	1
slave_busy_counter	9111	U16	1
bus_character_overrun_counter	9112	U16	1

link settings as documented (unverified): RTU/ASCII; default 19200 8E1; unit ID 34; RTU is Default Mode. Data Bits and Stop Bits are automatically selected based on Mode (RTU: 8 data, 1 stop; ASCII: 7 data, 2 stop).

bench facts as documented (unverified)

terminals	Terminal board (M2 version), M12 Connector (M3 version), Wire Cable pig tail (M4 version)
A/B polarity	D0 is RS485 -, D1 is RS485 +
termination	Internal programmable network termination enabled by Modbus command
connector	M12 or Terminal board or pig tail
shield/ground	Com/Reset GND
protocol notes	Write 0 to register 49007 to save user device identification registers. Write Modbus Address to 49007 to save communication settings and reboot.
model register	49561
serial register	49591
firmware register	49602
identification notes	Vendor Name at 49501, Product Code at 49516, Major/Minor Revision at 49526, Modbus Module Serial Number at 49596
power	12 to 24 VDC Nominal, 10.6 to 32 VDC max regulated. Do not exceed 32 VDC.
doc revision	3-9900.270.090 Rev 3 02/19

field reports — community-sourced, unverified (checked 2026-06-11)

Typo in the manual text on page 5: it references 'Register 490007' (6 digits) to save user device identification registers, whereas the correct register is 49007. [source]
The 9900 Transmitter in Batch mode (when the 3-9900.397 Batch Module is installed or when configured as a 9900-1BC Batch Controller) does not support the 3-9900.270-MX Modbus module or the 3-9900.395 HART Communication module. [source]
confirmed: Baud rates [1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200] with default 19200 — confirmed by GF Signet 9900 Modbus Module Manual (3-9900.270.090)
confirmed: Default Modbus Address (Unit ID) is 34 — confirmed by GF Signet 9900 Modbus Module Manual (3-9900.270.090)
confirmed: Modbus RTU and ASCII modes supported, with RTU as default — confirmed by GF Signet 9900 Modbus Module Manual (3-9900.270.090)
confirmed: Data bits and stop bits are automatically selected based on mode (RTU: 8 data, 1 stop; ASCII: 7 data, 2 stop) — confirmed by GF Signet 9900 Modbus Module Manual (3-9900.270.090)
confirmed: Default parity is Even (E) — confirmed by GF Signet 9900 Modbus Module Manual (3-9900.270.090)
confirmed: Power requirements are 12 to 24 VDC Nominal, 10.6 to 32 VDC max regulated — confirmed by GF Signet 9900 Modbus Module Manual (3-9900.270.090)
confirmed: RS485 polarity is D0 as RS485 - and D1 as RS485 + — confirmed by GF Signet 9900 Modbus Module Manual (3-9900.270.090)
confirmed: Shield ground is Com/Reset GND — confirmed by GF Signet 9900 Modbus Module Manual (3-9900.270.090)

The trust ladder

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

generated — A prompt produced it. Unproven — anyone can regenerate this.
structure-verified — Decode path is structurally sound (addresses, widths, finite values). Does NOT prove word order or scaling.
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.
hardware-verified (software-key) x1 — Matched a real device with operator-attested readings as ground truth — the only rung that confirms word order + scaling on the wire.

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