RKC FB100/FB400/FB900 controller (needs C5/C6 comms option)

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	unit
Measured value (PV)	0	I16	1
Current transformer 1 (CT1) input value monitor	1	U16	0.1	A
Current transformer 2 (CT2) input value monitor	2	U16	0.1	A
Set value (SV) monitor	3	I16	1
Remote setting (RS) input value monitor	4	I16	1
Burnout state monitor	5	U16	1
Burnout state monitor of feedback resistance input	6	U16	1
Event 1 state monitor	7	U16	1
Event 2 state monitor	8	U16	1
Event 3 state monitor	9	U16	1
Event 4 state monitor	10	U16	1
Heater break alarm 1 (HBA1) state monitor	11	U16	1
Heater break alarm 2 (HBA2) state monitor	12	U16	1
Manipulated output value (MV1) monitor [heat-side]	13	I16	0.1	%
Manipulated output value (MV2) monitor [cool-side]	14	I16	0.1	%
Error code	15	U16	1
Digital input (DI) state monitor	16	U16	1
Output state monitor	17	U16	1
Operation mode state monitor	18	U16	1
Memory area soak time monitor	19	U16	1
Integrated operating time monitor	20	U16	1	hours
Holding peak value ambient temperature monitor	21	I16	0.1	°C
Power feed forward input value monitor	22	U16	0.1	%
Backup memory state monitor	23	U16	1
PID/AT transfer	32	U16	1
Auto/Manual transfer	33	U16	1
Remote/Local transfer	34	U16	1
RUN/STOP transfer	35	U16	1
Memory area transfer	36	U16	1
Interlock release	37	U16	1
Event 1 set value (EV1)	38	I16	1
Event 2 set value (EV2)	39	I16	1
Event 3 set value (EV3)	40	I16	1
Event 4 set value (EV4)	41	I16	1
Control loop break alarm (LBA) time	42	U16	1	seconds
LBA deadband	43	U16	1
Set value (SV)	44	I16	1
Proportional band [heat-side]	45	U16	1
Integral time [heat-side]	46	U16	1	seconds
Derivative time [heat-side]	47	U16	1	seconds
Control response parameter	48	U16	1
Proportional band [cool-side]	49	U16	1
Integral time [cool-side]	50	U16	1	seconds
Derivative time [cool-side]	51	U16	1	seconds
Overlap/Deadband	52	I16	1
Manual reset	53	I16	1	%
Setting change rate limiter (up)	54	U16	1
Setting change rate limiter (down)	55	U16	1
Area soak time	56	U16	1
Link area number	57	U16	1
Heater break alarm 1 (HBA1) set value	58	U16	0.1	A
Heater break determination point 1	59	U16	0.1	%
Heater melting determination point 1	60	U16	0.1	%
Heater break alarm 2 (HBA2) set value	61	U16	0.1	A
Heater break determination point 2	62	U16	0.1	%
Heater melting determination point 2	63	U16	0.1	%
PV bias	64	I16	1
PV digital filter	65	U16	0.1	seconds
PV ratio	66	U16	0.001
PV low input cut-off	67	U16	0.01	%
RS bias	68	I16	1
RS digital filter	69	U16	0.1	seconds
RS ratio	70	U16	0.001
Proportional cycle time [heat-side]	71	U16	0.1	seconds
Proportional cycle time [cool-side]	72	U16	0.1	seconds
Manual manipulated output value	73	I16	1
Set lock level	74	U16	1
STOP display	75	U16	1
Bar graph display	76	U16	1
Bar graph display resolution	77	U16	1	digit/dot
Direct key 1	78	U16	1
Direct key 2	79	U16	1
Direct key 3	80	U16	1
Direct key type	81	U16	1
Input type	82	U16	1
Display unit	83	U16	1
Decimal point position	84	U16	1
Input scale high	85	I16	1
Input scale low	86	I16	1
Input error determination point (high)	87	I16	1
Input error determination point (low)	88	I16	1
Burnout direction	89	U16	1
Square root extraction	90	U16	1
Power supply frequency	91	U16	1	Hz
Sampling cycle	92	U16	1	ms
Remote setting input type	93	U16	1
Digital input (DI) assignment	94	U16	1
Output assignment	95	U16	1
Timer 1	96	U16	0.1	seconds
Timer 2	97	U16	0.1	seconds
Timer 3	98	U16	0.1	seconds
Timer 4	99	U16	0.1	seconds
Energized/De-energized	100	U16	1
Alarm (ALM) lamp lighting condition 1	101	U16	1
Alarm (ALM) lamp lighting condition 2	102	U16	1
Output status at STOP mode	103	U16	1
Transmission output type	110	U16	1
Transmission output scale high	111	I16	1
Transmission output scale low	112	I16	1
Event 1 type	113	U16	1
Event 1 hold action	114	U16	1
Event 1 interlock	115	U16	1
Event 1 differential gap	116	I16	1
Event 1 delay timer	117	U16	0.1	seconds
Force ON of Event 1 action	118	U16	1
Event 2 type	119	U16	1
Event 2 hold action	120	U16	1
Event 2 interlock	121	U16	1
Event 2 differential gap	122	I16	1
Event 2 delay timer	123	U16	0.1	seconds
Force ON of Event 2 action	124	U16	1
Event 3 type	125	U16	1
Event 3 hold action	126	U16	1
Event 3 interlock	127	U16	1
Event 3 differential gap	128	I16	1
Event 3 delay timer	129	U16	0.1	seconds
Force ON of Event 3 action	130	U16	1
Event 4 type	131	U16	1
Event 4 hold action	132	U16	1
Event 4 interlock	133	U16	1
Event 4 differential gap	134	I16	1
Event 4 delay timer	135	U16	0.1	seconds
Force ON of Event 4 action	136	U16	1
CT1 ratio	137	U16	1
CT1 assignment	138	U16	1
Heater break alarm 1 (HBA1) type	139	U16	1
Number of heater break alarm 1 (HBA1) delay times	140	U16	1	times
CT2 ratio	141	U16	1
CT2 assignment	142	U16	1
Heater break alarm 2 (HBA2) type	143	U16	1
Number of heater break alarm 2 (HBA2) delay times	144	U16	1	times
Hot/Cold start	145	U16	1
Start determination point	146	I16	1
External input type	147	U16	1
Master channel selection	148	U16	1
SV tracking	149	U16	1
MV transfer function	150	U16	1
Control action	151	U16	1
Integral/derivative time decimal point position	152	U16	1
Derivative action	153	U16	1
Undershoot suppression factor	154	U16	0.001
Derivative gain	155	U16	0.1
ON/OFF action differential gap (upper)	156	I16	1
ON/OFF action differential gap (lower)	157	I16	1
Action (high) at input error	158	U16	1
Action (low) at input error	159	U16	1
Manipulated output value at input error	160	I16	0.1	%
Manipulated output value (MV1) at STOP mode	161	I16	0.1	%
Manipulated output value (MV2) at STOP mode	162	I16	0.1	%
Output change rate limiter (up) [MV1]	163	I16	0.1	%/seconds
Output change rate limiter (down) [MV1]	164	I16	0.1	%/seconds
Output limiter high (MV1)	165	I16	0.1	%
Output limiter low (MV1)	166	I16	0.1	%
Output change rate limiter (up) [MV2]	167	I16	0.1	%/seconds
Output change rate limiter (down) [MV2]	168	I16	0.1	%/seconds
Output limiter high (MV2)	169	I16	0.1	%
Output limiter low (MV2)	170	I16	0.1	%
Power feed forward selection	171	U16	1
Power feed forward gain	172	U16	0.01
AT bias	173	I16	1
AT cycles	174	U16	1
Output value with AT turned on	175	I16	0.1	%
Output value with AT turned off	176	I16	0.1	%
AT differential gap time	177	U16	0.1	seconds
Proportional band adjusting factor [heat-side]	178	U16	0.01	times
Integral time adjusting factor [heat-side]	179	U16	0.01	times
Derivative time adjusting factor [heat-side]	180	U16	0.01	times
Proportional band adjusting factor [cool-side]	181	U16	0.01	times
Integral time adjusting factor [cool-side]	182	U16	0.01	times
Derivative time adjusting factor [cool-side]	183	U16	0.01	times
Proportional band limiter (high) [heat-side]	184	I16	1
Proportional band limiter (low) [heat-side]	185	I16	1
Integral time limiter (high) [heat-side]	186	I16	1	seconds
Integral time limiter (low) [heat-side]	187	I16	1	seconds
Derivative time limiter (high) [heat-side]	188	I16	1	seconds
Derivative time limiter (low) [heat-side]	189	I16	1	seconds
Proportional band limiter (high) [cool-side]	190	I16	1
Proportional band limiter (low) [cool-side]	191	I16	1
Integral time limiter (high) [cool-side]	192	I16	1	seconds
Integral time limiter (low) [cool-side]	193	I16	1	seconds
Derivative time limiter (high) [cool-side]	194	I16	1	seconds
Derivative time limiter (low) [cool-side]	195	I16	1	seconds
Open/Close output neutral zone	196	U16	0.1	%
Open/Close output differential gap	197	U16	0.1	%
Action at feedback resistance (FBR) input error	198	U16	1
Feedback adjustment	199	U16	1
Control motor time	200	U16	1	seconds
Integrated output limiter	201	U16	0.1	%
Valve action at STOP	202	U16	1
Startup tuning (ST)	203	U16	1
ST proportional band adjusting factor	204	U16	0.01	times
ST integral time adjusting factor	205	U16	0.01	times
ST derivative time adjusting factor	206	U16	0.01	times
ST start condition	207	U16	1
Automatic temperature rise group	208	U16	1
Automatic temperature rise learning	209	U16	1
Automatic temperature rise dead time	210	U16	0.1	seconds
Automatic temperature rise gradient data	211	U16	0.1
RUN/STOP group	212	U16	1
Setting change rate limiter unit time	213	U16	1	seconds
Soak time unit	214	U16	1
Setting limiter high	215	I16	1
Setting limiter low	216	I16	1
PV transfer function	217	U16	1
PV flashing display at input error	218	U16	1
Overlap/Deadband reference point	219	U16	0.1
Action at saturated output	220	U16	1
Control area Local/External transfer	224	U16	1
Setting memory area number	1280	U16	1
Event 1 set value (EV1)	1281	I16	1
Event 2 set value (EV2)	1282	I16	1
Event 3 set value (EV3)	1283	I16	1
Event 4 set value (EV4)	1284	I16	1
Control loop break alarm (LBA) time	1285	U16	1	seconds
LBA deadband	1286	U16	1
Set value (SV)	1287	I16	1
Proportional band [heat-side]	1288	I16	1
Integral time [heat-side]	1289	I16	1	seconds
Derivative time [heat-side]	1290	I16	1	seconds
Control response parameter	1291	U16	1
Proportional band [cool-side]	1292	I16	1
Integral time [cool-side]	1293	I16	1	seconds
Derivative time [cool-side]	1294	I16	1	seconds
Overlap/Deadband	1295	I16	1
Manual reset	1296	I16	0.1	%
Setting change rate limiter (up)	1297	I16	1
Setting change rate limiter (down)	1298	I16	1
Area soak time	1299	U16	1
Link area number	1300	U16	1
Register address setting 1	4096	U16	1
Register address setting 2	4097	U16	1
Register address setting 3	4098	U16	1
Register address setting 4	4099	U16	1
Register address setting 5	4100	U16	1
Register address setting 6	4101	U16	1
Register address setting 7	4102	U16	1
Register address setting 8	4103	U16	1
Register address setting 9	4104	U16	1
Register address setting 10	4105	U16	1
Register address setting 11	4106	U16	1
Register address setting 12	4107	U16	1
Register address setting 13	4108	U16	1
Register address setting 14	4109	U16	1
Register address setting 15	4110	U16	1
Register address setting 16	4111	U16	1
Data specified by register address setting 1	5376	U16	1
Data specified by register address setting 2	5377	U16	1
Data specified by register address setting 3	5378	U16	1
Data specified by register address setting 4	5379	U16	1
Data specified by register address setting 5	5380	U16	1
Data specified by register address setting 6	5381	U16	1
Data specified by register address setting 7	5382	U16	1
Data specified by register address setting 8	5383	U16	1
Data specified by register address setting 9	5384	U16	1
Data specified by register address setting 10	5385	U16	1
Data specified by register address setting 11	5386	U16	1
Data specified by register address setting 12	5387	U16	1
Data specified by register address setting 13	5388	U16	1
Data specified by register address setting 14	5389	U16	1
Data specified by register address setting 15	5390	U16	1
Data specified by register address setting 16	5391	U16	1

link settings as documented (unverified): RTU; default 19200 8N1; unit ID 0; FC 03,06,08,16; Modbus protocol identifies the host computer as master, the controller as slave.

⚠ An external protection device must be installed if failure of this instrument could result in damage to the instrument, equipment or injury to personnel. — Starkest reads only; we never write a control register.

bench facts as documented (unverified)

terminals	FB100: 13 (SG), 14 (T/R A), 15 (T/R B). FB400/900: 25 (SG), 26 (T/R A), 27 (T/R B)
A/B polarity	V(A) - V(B) >= 2V -> 0 (SPACE), V(A) - V(B) <= -2V -> 1 (MARK)
termination	Externally terminal connected (RS-485)
connector	Screw terminals (M3 x 7 with 5.8 x 5.8 square washer)
isolation	Reinforced insulation between input signal wires and power supply/load wires
shield/ground	Shielded twisted pair wire recommended
max registers/read	125
inter-frame delay	4 ms
broadcast	not supported
protocol notes	Commands should be sent at time intervals of 30 bits after the master receives the response message.
doc revision	IMR01W04-E6

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

confirmed: comms.baud_rates: [2400, 4800, 9600, 19200, 38400] — confirmed by RKC FB100/FB400/FB900 Communication Instruction Manual (IMR01W04-E6)
confirmed: comms.default_baud: 19200 — confirmed by RKC FB100/FB400/FB900 Communication Instruction Manual (IMR01W04-E6)
confirmed: comms.default_unit_id: 0 — confirmed by RKC FB100/FB400/FB900 Communication Instruction Manual (IMR01W04-E6)
confirmed: comms.function_codes: [3, 6, 8, 16] — confirmed by RKC FB100/FB400/FB900 Communication Instruction Manual (IMR01W04-E6)
confirmed: facts.doc_revision: IMR01W04-E6 — confirmed by RKC FB100/FB400/FB900 Communication Instruction Manual (IMR01W04-E6)
confirmed: physical.connector: Screw terminals (M3 x 7 with 5.8 x 5.8 square washer) — confirmed by RKC FB100/FB400/FB900 Communication Instruction Manual (IMR01W04-E6)
confirmed: physical.terminals: FB100: 13 (SG), 14 (T/R A), 15 (T/R B). FB400/900: 25 (SG), 26 (T/R A), 27 (T/R B) — confirmed by RKC FB100/FB400/FB900 Communication Instruction Manual (IMR01W04-E6)
confirmed: physical.polarity: V(A) - V(B) >= 2V -> 0 (SPACE), V(A) - V(B) <= -2V -> 1 (MARK) — confirmed by RKC FB100/FB400/FB900 Communication Instruction Manual (IMR01W04-E6)

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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