Trane · Chiller
Ascend ACRB air-cooled chiller (Symbio 800 controls) Modbus register map
Default configuration
- Protocol
- Modbus TCP
- Port
- 502
- Unit ID
- 1
- Addressing
- 1-based
- Byte order
- Big endian
- Word order
- High word first
Register map
| Address | Count | Name | Type | Unit | Scale | Access |
|---|---|---|---|---|---|---|
| 11 | 2 | Active chilled water setpoint Chilled water setpoint the chiller is currently controlling to, after arbitration between BAS, external and front-panel sources. | Float32 | °F | 1 | R |
| 13 | 2 | Evaporator entering water temperature Water temperature entering the evaporator (return from the cooling load). | Float32 | °F | 1 | R |
| 15 | 2 | Evaporator leaving water temperature Water temperature leaving the evaporator (supply to the cooling load). | Float32 | °F | 1 | R |
| 17 | 2 | Calculated chiller capacity Cooling capacity the chiller is currently delivering, in tons of refrigeration. | Float32 | ton | 1 | R |
| 19 | 2 | Active demand limit setpoint Demand limit the chiller is currently applying. | Float32 | % | 1 | R |
| 21 | 2 | Unit power consumption Electrical input power of the whole chiller. | Float32 | kW | 1 | R |
| 25 | 2 | Outdoor air temperature Ambient temperature at the unit. | Float32 | °F | 1 | R |
| 27 | 2 | Evaporator refrigerant pressure, circuit 1 Refrigerant pressure in the evaporator of circuit 1. | Float32 | psi | 1 | R |
| 29 | 2 | Condenser refrigerant pressure, circuit 1 Refrigerant pressure in the condenser of circuit 1. | Float32 | psi | 1 | R |
| 31 | 2 | Differential refrigerant pressure, circuit 1 Difference between discharge and suction pressure on circuit 1. | Float32 | psi | 1 | R |
| 33 | 2 | Evaporator saturated refrigerant temperature, circuit 1 Saturated refrigerant temperature in the evaporator of circuit 1. | Float32 | °F | 1 | R |
| 35 | 2 | Condenser saturated refrigerant temperature, circuit 1 Saturated refrigerant temperature in the condenser of circuit 1. | Float32 | °F | 1 | R |
| 37 | 2 | Evaporator refrigerant pressure, circuit 2 Refrigerant pressure in the evaporator of circuit 2. | Float32 | psi | 1 | R |
| 39 | 2 | Condenser refrigerant pressure, circuit 2 Refrigerant pressure in the condenser of circuit 2. | Float32 | psi | 1 | R |
| 41 | 2 | Differential refrigerant pressure, circuit 2 Difference between discharge and suction pressure on circuit 2. | Float32 | psi | 1 | R |
| 43 | 2 | Evaporator saturated refrigerant temperature, circuit 2 Saturated refrigerant temperature in the evaporator of circuit 2. | Float32 | °F | 1 | R |
| 45 | 2 | Condenser saturated refrigerant temperature, circuit 2 Saturated refrigerant temperature in the condenser of circuit 2. | Float32 | °F | 1 | R |
| 47 | 2 | Refrigerant discharge temperature, compressor 1A Discharge gas temperature of compressor 1A. | Float32 | °F | 1 | R |
| 49 | 2 | Oil pressure, compressor 1A Oil pressure on the high-pressure side of compressor 1A. | Float32 | psi | 1 | R |
| 51 | 2 | Refrigerant discharge temperature, compressor 2A Discharge gas temperature of compressor 2A. | Float32 | °F | 1 | R |
| 53 | 2 | Oil pressure, compressor 2A Oil pressure on the high-pressure side of compressor 2A. | Float32 | psi | 1 | R |
| 55 | 2 | Air flow percentage, circuit 1 Approximate air flow through circuit 1. | Float32 | % | 1 | R |
| 57 | 2 | Air flow percentage, circuit 2 Approximate air flow through circuit 2. | Float32 | % | 1 | R |
| 59 | 2 | Starts, compressor 1A Number of starts of compressor 1A. | Float32 | - | 1 | R |
| 61 | 2 | Run time, compressor 1A Accumulated run time of compressor 1A. | Float32 | h | 1 | R |
| 63 | 2 | Compressor 1A speed status Percentage of available speed currently used by compressor 1A. | Float32 | % | 1 | R |
| 69 | 2 | Drive motor current U, compressor 1A (RLA) Line 1 current at the compressor 1A drive, as a percentage of rated load amps. | Float32 | % | 1 | R |
| 71 | 2 | Drive motor current V, compressor 1A (RLA) Line 2 current at the compressor 1A drive, as a percentage of rated load amps. | Float32 | % | 1 | R |
| 73 | 2 | Drive motor current W, compressor 1A (RLA) Line 3 current at the compressor 1A drive, as a percentage of rated load amps. | Float32 | % | 1 | R |
| 93 | 2 | Drive output power, circuit 1 Power delivered by the compressor drive of circuit 1. | Float32 | kW | 1 | R |
| 111 | 2 | Starts, compressor 2A Number of starts of compressor 2A. | Float32 | - | 1 | R |
| 113 | 2 | Run time, compressor 2A Accumulated run time of compressor 2A. | Float32 | h | 1 | R |
| 173 | 2 | Energy consumption, lifetime Total electrical energy consumed by the unit since commissioning. | Float32 | kWh | 1 | R |
| 181 | 2 | Active cool/heat setpoint temperature Active setpoint for the current mode (cooling or heating). | Float32 | °F | 1 | R |
| 2010 | 1 | Running mode 1 = Chiller off, 2 = Chiller in start mode, 3 = Chiller in run mode, 4 = Chiller in pre-shutdown mode, 5 = Chiller in service mode. | UInt16 | - | 1 | R |
| 2011 | 1 | Operating mode 1 = Cool, 2 = Heat, 3 = Ice making, 4 = Free cooling. | UInt16 | - | 1 | R |
| 2012 | 1 | Chiller setpoint source 1 = BAS, 2 = External, 3 = Front panel. | UInt16 | - | 1 | R |
| 3010 | 1 | Run enable 0 = Run not enabled, 1 = Run enabled. | Int16 | - | 1 | R |
| 3011 | 1 | Local setpoint control 0 = Remote control, 1 = Local control. | Int16 | - | 1 | R |
| 3013 | 1 | Chiller running state 0 = Off, 1 = On. | Int16 | - | 1 | R |
| 3015 | 1 | Evaporator water pump command 0 = Off, 1 = On. Request from the chiller to run the evaporator water pump. | Int16 | - | 1 | R |
| 3016 | 1 | Evaporator water flow status 1 = Flow, 0 = No flow (the chiller may refuse to start). | Int16 | - | 1 | R |
| 3018 | 1 | Emergency stop 0 = Auto, 1 = Emergency stop, manual reset required. | Int16 | - | 1 | R |
| 3019 | 1 | Diagnostic present 1 = In alarm, 0 = Normal. | Int16 | - | 1 | R |
| 3020 | 1 | Diagnostic shutdown present 1 = Chiller is shut down by a diagnostic, 0 = Normal. | Int16 | - | 1 | R |
| 3021 | 1 | Diagnostic: manual reset required 1 = A diagnostic requiring manual reset is active, 0 = Normal. | Int16 | - | 1 | R |
| 3025 | 1 | Diagnostic present: critical 1 = Critical-category diagnostic present, 0 = Normal. | Int16 | - | 1 | R |
| 3026 | 1 | Diagnostic present: service required 1 = Service-required diagnostic present, 0 = Normal. | Int16 | - | 1 | R |
| 3027 | 1 | Running status, compressor 1A 0 = Off, 1 = Running. | Int16 | - | 1 | R |
| 3028 | 1 | Running status, compressor 2A 0 = Off, 1 = Running. | Int16 | - | 1 | R |
| 3029 | 1 | Free cooling active 0 = Inactive, 1 = Active. | Int16 | - | 1 | R |
| 3030 | 1 | External auto/stop State of the hard-wired auto/stop input: 0 = Stop, 1 = Auto. | Int16 | - | 1 | R |
| 3032 | 1 | Noise reduction request active 0 = Off, 1 = On. | Int16 | - | 1 | R |
Notes
This is the Modbus points list for Ascend ACRB 150-300 ton chillers with Symbio 800 controls (Trane integration guide BAS-SVP045B-EN). Larger ACRB 350-500 ton units use a different set of register numbers with the same object names, so check the points list for your unit size. Symbio 800 serves Modbus TCP on Ethernet port 1 once the system protocol is set to Modbus TCP in the controller; the rotary address applies only to Modbus RTU, so the unit identifier is not used for TCP and 1 is sent here. Addresses are the register numbers from the Trane points list without their Modicon area prefix (input register 30011 is listed as 11, holding register 40010 as 10), one-based, so the wire address is the number minus one; Float32 values occupy two registers and are transmitted big-endian, high word first. Values are US units (degrees Fahrenheit, psi, tons of refrigeration). Port 2 of the controller is reserved for the TD7 display.