Trane Ascend/Symbio chiller controller

Register map(s) for this device, each at the trust rung it earned. Addresses are 0-based as on the wire. Word order and scaling are confirmed at the hardware-verified rung and at no rung below it.

interop-verified

Read + decoded cleanly over a real network vs an independent third-party Modbus test server (transport and framing; reads are remapped into the server's register window, so the map's own addresses are NOT exercised). Does NOT prove word order/scaling against the actual device.

point	address (0-based)	type	scale
active_chilled_water_setpoint	10	F32BE	1
evaporator_entering_water_temperature	12	F32BE	1
evaporator_leaving_water_temperature	14	F32BE	1
calculated_chiller_capacity	16	F32BE	1
active_demand_limit_setpoint	18	F32BE	1
unit_power_consumption	20	F32BE	1
outdoor_air_temperature	24	F32BE	1
evaporator_refrigerant_pressure_circuit_1	26	F32BE	1
condenser_refrigerant_pressure_circuit_1	28	F32BE	1
differential_refrigerant_pressure_circuit_1	30	F32BE	1
evaporator_saturated_refrigerant_temperature_circuit_1	32	F32BE	1
condenser_saturated_refrigerant_temperature_circuit_1	34	F32BE	1
evaporator_refrigerant_pressure_circuit_2	36	F32BE	1
condenser_refrigerant_pressure_circuit_2	38	F32BE	1
differential_refrigerant_pressure_circuit_2	40	F32BE	1
evaporator_saturated_refrigerant_temperature_circuit_2	42	F32BE	1
condenser_saturated_refrigerant_temperature_circuit_2	44	F32BE	1
refrigerant_discharge_temperature_compressor_1a	46	F32BE	1
oil_pressure_compressor_1a	48	F32BE	1
refrigerant_discharge_temperature_compressor_2a	50	F32BE	1
oil_pressure_compressor_2a	52	F32BE	1
air_flow_percentage_circuit_1	54	F32BE	1
air_flow_percentage_circuit_2	56	F32BE	1
starts_compressor_1a	58	F32BE	1
run_time_compressor_1a	60	F32BE	1
compressor_1a_speed_status	62	F32BE	1
motor_winding_temperature_1_circuit_1	64	F32BE	1
motor_winding_temperature_2_circuit_1	66	F32BE	1
drive_motor_current_u_rla_compressor_1a	68	F32BE	1
drive_motor_current_v_rla_compressor_1a	70	F32BE	1
drive_motor_current_w_rla_compressor_1a	72	F32BE	1
drive_motor_average_current_rla_compressor_1a	74	F32BE	1
drive_motor_current_u_compressor_1a	76	F32BE	1
drive_motor_current_v_compressor_1a	78	F32BE	1
drive_motor_current_w_compressor_1a	80	F32BE	1
drive_motor_voltage_uv_circuit_1	82	F32BE	1
drive_motor_voltage_vw_circuit_1	84	F32BE	1
drive_motor_voltage_wu_circuit_1	86	F32BE	1
drive_motor_average_voltage_circuit_1	88	F32BE	1
drive_dc_bus_voltage_circuit_1	90	F32BE	1
drive_output_power_circuit_1	92	F32BE	1
drive_input_power_circuit_1	94	F32BE	1
drive_line_average_voltage_circuit_1	96	F32BE	1
drive_average_line_current_circuit_1	98	F32BE	1
drive_line_frequency_circuit_1	100	F32BE	1
afd_frequency_circuit_1	102	F32BE	1
afd_transistor_temperature_circuit_1	104	F32BE	1
drive_inverter_base_temperature_circuit_1	106	F32BE	1
drive_rectifier_base_temperature_circuit_1	108	F32BE	1
starts_compressor_2a	110	F32BE	1
run_time_compressor_2a	112	F32BE	1
compressor_2a_speed_status	114	F32BE	1
motor_winding_temperature_1_circuit_2	116	F32BE	1
motor_winding_temperature_2_circuit_2	118	F32BE	1
drive_motor_current_u_rla_compressor_2a	120	F32BE	1
drive_motor_current_v_rla_compressor_2a	122	F32BE	1
drive_motor_current_w_rla_compressor_2a	124	F32BE	1
drive_motor_average_current_rla_compressor_2a	126	F32BE	1
drive_motor_current_u_compressor_2a	128	F32BE	1
drive_motor_current_v_compressor_2a	130	F32BE	1
drive_motor_current_w_compressor_2a	132	F32BE	1
drive_motor_voltage_uv_circuit_2	134	F32BE	1
drive_motor_voltage_vw_circuit_2	136	F32BE	1
drive_motor_voltage_wu_circuit_2	138	F32BE	1
drive_motor_average_voltage_circuit_2	140	F32BE	1
drive_dc_bus_voltage_circuit_2	142	F32BE	1
drive_output_power_circuit_2	144	F32BE	1
drive_input_power_circuit_2	146	F32BE	1
drive_line_average_voltage_circuit_2	148	F32BE	1
drive_average_line_current_circuit_2	150	F32BE	1
drive_line_frequency_circuit_2	152	F32BE	1
afd_frequency_circuit_2	154	F32BE	1
afd_transistor_temperature_circuit_2	156	F32BE	1
drive_inverter_base_temperature_circuit_2	158	F32BE	1
drive_rectifier_base_temperature_circuit_2	160	F32BE	1
free_cooling_capacity	168	F32BE	1
free_cooling_entering_water_temperature	170	F32BE	1
energy_consumption_lifetime	172	F32BE	1
energy_consumption	174	F32BE	1
chiller_design_capacity	178	F32BE	1
active_cool_heat_setpoint_temperature	180	F32BE	1
actual_running_capacity	182	F32BE	1
bas_chilled_water_setpoint	9	F32BE	1
bas_demand_limit_setpoint	11	F32BE	1
run_enable	3009	I16	1
chiller_running_state	3012	I16	1
running_mode	2009	U16	1
operating_mode	2010	U16	1

link settings as documented (unverified): RTU/TCP; default 19200 8E1; The valid range of Modbus RTU server addresses is 001–247. Rotary address 000 disables Modbus RTU communications.

bench facts as documented (unverified)

terminals	P1 Link (+ and - terminals)
A/B polarity	Observe wire polarity when connecting to the + and - terminals. The + terminals and the - terminals are internally connected.
connector	RJ-45 for Modbus TCP on Ethernet port 1
wiring notes	P1 Link is used for RS-485 daisy chain.
protocol notes	The Symbio 800 controller does not support the optional Wi-Fi module with Modbus TCP communications.
power	Power for the controller is provided and connected from within the chiller control panel.
doc revision	BAS-SVP045B-EN

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

Modbus communication errors can occur on Symbio 800 controllers due to harness damage, water intrusion in plug connections, or electromagnetic interference if the Modbus cable is not separated from the control power transformer as it exits the top of the control box. [source]
confirmed: comms.default_baud: 19200 — confirmed by Trane Integration Guide BAS-SVP045B-EN, which lists the default baud rate as 19200 bps [2.3.1].
confirmed: comms.framing: ['RTU', 'TCP'] — confirmed by Trane Integration Guide BAS-SVP045B-EN, which details configuration for both Modbus RTU and Modbus TCP.
confirmed: comms.notes: The valid range of Modbus RTU server addresses is 001–247. Rotary address 000 disables Modbus RTU communications. — confirmed by Trane Integration Guide BAS-SVP045B-EN, which states that the valid range is 001-247 and setting the rotary address to 000 disables Modbus RTU communications.
confirmed: comms.parity: E — confirmed by Trane Integration Guide BAS-SVP045B-EN, which lists the default parity as Even.
confirmed: comms.stop_bits: 1 — confirmed by Trane Integration Guide BAS-SVP045B-EN, which lists the default stop bits as 1.
confirmed: facts.doc_revision: BAS-SVP045B-EN — confirmed by the official Trane document title 'BACnet® and Modbus Integration to Ascend™ Air-Cooled Chiller Model ACR with Symbio™ 800 Controls'.
confirmed: facts.physical.connector: RJ-45 for Modbus TCP on Ethernet port 1 — confirmed by Trane Integration Guide BAS-SVP045B-EN, which instructs to connect an Ethernet cable with RJ-45 connectors to Ethernet port 1.
confirmed: facts.physical.notes: P1 Link is used for RS-485 daisy chain. — confirmed by Trane Integration Guide BAS-SVP045B-EN, which states P1 Link is used for RS-485 daisy chain connection to a primary controller.

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.
interop-verified — Read + decoded cleanly over a real network vs an independent third-party Modbus test server (transport and framing; reads are remapped into the server's register window, so the map's own addresses are NOT exercised). Does NOT prove word order/scaling against the actual device.
simulator-verified — Decoded correctly against a protocol emulator seeded with known-true values — catches word-order/scaling errors vs the emulator, not the physical device.
hardware-verified x1 — Matched a real device with operator-attested readings as ground truth — the only rung that confirms word order + scaling on the wire.

If your device isn't here, upload its register map. Generation is free, and the connector keeps the rung it earns under testing.

To prove a connector against your own device, order hardware verification. If it doesn't verify, you don't pay.

Platform builders can license the verified library: machine-readable maps, the firmware matrix, API access.