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Humidifier controller · BACnet points list
DriSteem Vapor-logic 4 BACnet points list
Updated 12 November 2026
Vapor-logic 4 is an older generation (before Vapor-logic 5 and 6) of the DriSteem humidifier control board. Modbus is standard; BACnet MS/TP (terminal P7) or BACnet IP (Ethernet) is an option bought with an unlock code. Its interoperability table lists 95 BACnet objects, plus 5 multi-tank objects in a separate table (100 in all), with underscore-style names: RH, dew point and demand readings, setpoints and fieldbus demand, run mode, digital I/O, and alarm and message flags.
This page lists 100 BACnet objects for the DriSteem Vapor-logic 4 — 69 of them writable — with each object’s type, instance number, name, engineering units and access. It is re-typed from DriSteem’s own free documentation, linked below.
- Manufacturer
- DriSteem
- Model
- Vapor-logic 4
- Equipment
- Humidifier controller
- Equipment type
- Humidifiers
- BACnet objects
- 100 (69 writable)
- Transport
- BACnet MS/TP, BACnet IP
- Firmware
- Not stated
- Default device instance
- 255
- Also known as
- Vapor-logic4, Vapor-logic version 4, VL4, Vaporlogic 4, DriSteem humidifier controller (legacy)
Reference only, provided as-is: verify against DriSteem’s current documentation and the live device before use. Not official DriSteem information. Terms of use.
BMS integration notes: DriSteem Vapor-logic 4
Unlock and enable BACnet on the keypad (Setup > Communications > BACnet), set the device instance and MS/TP station or IP settings and cycle power. Then either write the space RH setpoint (AV 5) and let Vapor-logic control, or send a demand from the BMS (AV 8 / AV 9), and use MSV 1 Run_mode for auto/standby/drain.
Minimum points to map
The short list most integrators start with — enough to run the unit from a BMS. Map more as the job needs.
| Object | Name | Why | Access |
|---|---|---|---|
| MV 1 | Run_mode | Run mode: 1 auto, 2/3 standby, 4 drain | Write |
| AV 9 | Fieldbus_demand_% | Demand from the BMS, % of capacity | Write |
| AV 5 | Space_RH_set_point | Space RH setpoint (unit controls) | Write |
| BV 4 | Clear_all_faults | Write 1 to clear faults | Write |
| AI 1 | Space_RH | Space RH | Read |
| AV 2 | Steam_output_percent | Estimated steam output, % | Read |
| AI 5 | Steam_demand_percent | Demand the unit is acting on, % | Read |
| BV 3 | Active_manually_cleared_alarms_exist | A manual-clear alarm exists | Read |
Enable & remote start
Run_mode (MSV 1) selects Auto, Local standby, System standby or Manual drain. The humidifier also needs its safety interlock and airflow inputs made (BI 1-3 show their state).
Sensors & values from the BMS
The space, dew point and duct RH values are read-only AIs from the unit's own transmitters; the BMS can send a demand (AV 8 mass or AV 9 percent, write-only) instead.
Network setup
- Device instance default 255; MS/TP station 1, max masters 127; default comm channel 19200 MS/TP; BACnet IP UDP port 47808.
- BACnet is an option: enter the purchased unlock code (matched to the serial number), pick the channel, then cycle power.
- MS/TP wiring lands on terminal P7; BACnet IP uses the Ethernet port.
Watch out for
- Fieldbus demand objects are write-only.
- Alarm and message BVs are listed RW but report conditions; clear faults with BV 4.
- Many objects only apply to one humidifier type.
DriSteem Vapor-logic 4 BACnet objects
Type: AI, AO, AV, BI, BO, BV, MI/MO/MV (multi-state) · Access: Read read-only, Write writable, Command writable with a priority array.
| Description | States | |||||
|---|---|---|---|---|---|---|
| AImin | 1 | Space_RH | % | Read | ||
| AI | 2 | Space_dew_point | °F | Read | ||
| AI | 3 | Duct_RH | % | Read | ||
| AI | 4 | Steam_demand_mass | lbs/hr | Read | ||
| AImin | 5 | Steam_demand_percent | % | Read | ||
| AI | 6 | Aux_temp | °F | Read | ||
| AI | 7 | Tank_temp | °F | Read | ||
| AI | 8 | MT_steam_demand_mass | Multi-tank system steam output, mass/hr | lbs/hr | Read | |
| AI | 9 | MT_steam_demand_percent | Multi-tank system steam output, % of system capacity | % | Read | |
| AI | 10 | Current_1 (XT systems only) | A | Read | ||
| AI | 11 | Current_2 (XT systems only) | A | Read | ||
| AV | 1 | Steam_output_mass | lbs/hr | Read | ||
| AVmin | 2 | Steam_output_percent | % | Read | ||
| AV | 3 | Water_until_ADS | 100 lbs | Read | ||
| AV | 4 | Water_until_service | 100 lbs | Read | ||
| AVmin | 5 | Space_RH_set_point | % | Write | ||
| AV | 6 | Space_dew_point_set_point | °F | Write | ||
| AV | 7 | Duct_high_limit_set_point | % | Write | ||
| AV | 8 | Fieldbus_demand_mass | Write-only demand from the BMS | lbs/hr | Write | |
| AVmin | 9 | Fieldbus_demand_% | Write-only demand from the BMS | % | Write | |
| AV | 10 | PID_band | % | Write | ||
| AV | 11 | PID-Kp | Write | |||
| AV | 12 | PID-Ki | Write | |||
| AV | 13 | PID-Kd | Write | |||
| AV | 14 | MT_steam_output_req_mass | Fieldbus steam request for the multi-tank system, mass/hr | lbs/hr | Write | |
| AV | 15 | MT_steam_output_req_pcnt | Fieldbus steam request, % of system | % | Write | |
| BI | 1 | Airflow_proving_switch | Read | |||
| BI | 2 | Duct_HL_switch | Read | |||
| BI | 3 | Safety_interlock | Read | |||
| BI | 4 | Combustion_air_damper_(GTS) | Read | |||
| BI | 5 | Flue_pressure_switch_(GTS) | Read | |||
| BI | 6 | Power_vent_switch_(GTS) / XV_header_status_(STS) | Read | |||
| BI | 7 | Low_water_sensor_(GTS) | Read | |||
| BI | 8 | Active_fault_exists / MT_active_fault_in_system | Read | |||
| BI | 9 | Active_message_exists / MT_active_message_in_system | Read | |||
| BI | 10 | High_water_sensor | Read | |||
| BI | 11 | High_water_sensor_2 | Read | |||
| BO | 1 | Fill_valve | Read | |||
| BO | 2 | Drain_valve | Read | |||
| BV | 1 | Active_messages_exist | Read | |||
| BV | 2 | Active_auto_cleared_alarms_exist | Read | |||
| BVmin | 3 | Active_manually_cleared_alarms_exist | Read | |||
| BVmin | 4 | Clear_all_faults | Write | |||
| BV | 5 | Alarm_tank_temp_sensor_failed | Alarm flag | Write | ||
| BV | 6 | Alarm_tank_overtemp | Alarm flag | Write | ||
| BV | 7 | Alarm_RH_signal_out_of_range | Also printed as Alarm_dew_pt_sig_out_of_range / Alarm_demand_sig_out_of_range | Write | ||
| BV | 8 | Alarm_duct_RH_sig_out_of_range | Alarm flag | Write | ||
| BV | 9 | Alarm_aux_temp_sens_out_of_rnge | Alarm flag | Write | ||
| BV | 10 | Alarm_water_probe_miswired | Alarm flag | Write | ||
| BV | 11 | Alarm_water_probe_failed | Alarm flag | Write | ||
| BV | 12 | Alarm_excess_fill_time | Alarm flag | Write | ||
| BV | 13 | Alarm_excess_refill_time | Alarm flag | Write | ||
| BV | 14 | Alarm_tank_not_draining | Alarm flag | Write | ||
| BV | 15 | Alarm_excess_water_no_demand | Alarm flag | Write | ||
| BV | 16 | Alarm_no_SDU_airflow | Alarm flag | Write | ||
| BV | 17 | Alarm_no_power_vent_airflow | Alarm flag | Write | ||
| BV | 18 | Alarm_no_combustion_airflow | Alarm flag | Write | ||
| BV | 19 | Alarm_blocked_flue | Alarm flag | Write | ||
| BV | 20 | Alarm_burner_1_failed | Alarm flag | Write | ||
| BV | 21 | Alarm_burner_2_failed | Alarm flag | Write | ||
| BV | 22 | Alarm_burner_3_failed | Alarm flag | Write | ||
| BV | 23 | Alarm_burner_4_failed | Alarm flag | Write | ||
| BV | 24 | Alarm_ignition_module_1_failed | Alarm flag | Write | ||
| BV | 25 | Alarm_ignition_module_2_failed | Alarm flag | Write | ||
| BV | 26 | Alarm_ignition_module_3_failed | Alarm flag | Write | ||
| BV | 27 | Alarm_ignition_module_4_failed | Alarm flag | Write | ||
| BV | 28 | Alarm_blower_1_failed | Alarm flag | Write | ||
| BV | 29 | Alarm_blower_2_failed | Alarm flag | Write | ||
| BV | 30 | Alarm_blower_3_failed | Alarm flag | Write | ||
| BV | 31 | Alarm_blower_4_failed | Alarm flag | Write | ||
| BV | 32 | Alarm_gas_valve_1_failed | Alarm flag | Write | ||
| BV | 33 | Alarm_gas_valve_2_failed | Alarm flag | Write | ||
| BV | 34 | Alarm_gas_valve_3_failed | Alarm flag | Write | ||
| BV | 35 | Alarm_gas_valve_4_failed | Alarm flag | Write | ||
| BV | 36 | Alarm_low_water | Alarm flag | Write | ||
| BV | 37 | Alarm_foaming_fault_2 | Alarm flag | Write | ||
| BV | 38 | Message_replace_contactors | Message flag | Write | ||
| BV | 39 | Message_service_unit | Message flag | Write | ||
| BV | 40 | Message_drain_pending | Message flag | Write | ||
| BV | 41 | Message_no_duct_airflow | Message flag | Write | ||
| BV | 42 | Message_interlock_open | Message flag | Write | ||
| BV | 43 | Message_freeze_prevent_draining | Message flag | Write | ||
| BV | 44 | Message_end-of-season_active | Message flag | Write | ||
| BV | 45 | Message_temp_comp_on | Message flag | Write | ||
| BV | 46 | Message_clean_probes | Message flag | Write | ||
| BV | 47 | Message_duct_HL_trip | Message flag | Write | ||
| BV | 48 | Message_duct_HL_span | Message flag | Write | ||
| BV | 49 | Message_insufficient_water | Message flag | Write | ||
| BV | 50 | Message_boiling_temp_calibrated | Message flag | Write | ||
| BV | 51 | Alarm_Current_Sense1_Out_Of_Range | Alarm flag | Write | ||
| BV | 52 | Alarm_Current_Sense2_Out_Of_Range | Alarm flag | Write | ||
| BV | 53 | Alarm_Overcurrent | Alarm flag | Write | ||
| BV | 54 | Alarm_Supply_Water | Alarm flag | Write | ||
| BV | 55 | Alarm_Foaming_Fault | Alarm flag | Write | ||
| BV | 56 | Message_Check_Cylinder | Message flag | Write | ||
| BV | 57 | Alarm_Overcurrent_2 | Alarm flag | Write | ||
| BV | 58 | Alarm_Supply_Water_2 | Alarm flag | Write | ||
| BV | 59 | Message_Check_Cylinder_2 | Message flag | Write | ||
| MVmin | 1 | Run_mode | Run mode (write 1-4; reads 1-6) | Write | 1=Auto, 2=Local standby, 3=System standby, 4=Manual drain, 5=Test outputs, 6=Test run | |
| MV | 2 | MT_Runmode | Multi-tank run mode | Write | 1=System standby, 2=System auto |
No points match these filters.
Object ID lookup: DriSteem Vapor-logic 4 point IDs by name
AI1Space_RHAI2Space_dew_pointAI3Duct_RHAI4Steam_demand_massAI5Steam_demand_percentAI6Aux_tempAI7Tank_tempAI8MT_steam_demand_massAI9MT_steam_demand_percentAI10Current_1 (XT systems only)AI11Current_2 (XT systems only)AV1Steam_output_massAV2Steam_output_percentAV3Water_until_ADSAV4Water_until_serviceAV5Space_RH_set_pointAV6Space_dew_point_set_pointAV7Duct_high_limit_set_pointAV8Fieldbus_demand_massAV9Fieldbus_demand_%AV10PID_bandAV11PID-KpAV12PID-KiAV13PID-KdAV14MT_steam_output_req_massAV15MT_steam_output_req_pcntBI1Airflow_proving_switchBI2Duct_HL_switchBI3Safety_interlockBI4Combustion_air_damper_(GTS)BI5Flue_pressure_switch_(GTS)BI6Power_vent_switch_(GTS) / XV_header_status_(STS)BI7Low_water_sensor_(GTS)BI8Active_fault_exists / MT_active_fault_in_systemBI9Active_message_exists / MT_active_message_in_systemBI10High_water_sensorBI11High_water_sensor_2BO1Fill_valveBO2Drain_valveBV1Active_messages_existBV2Active_auto_cleared_alarms_existBV3Active_manually_cleared_alarms_existBV4Clear_all_faultsBV5Alarm_tank_temp_sensor_failedBV6Alarm_tank_overtempBV7Alarm_RH_signal_out_of_rangeBV8Alarm_duct_RH_sig_out_of_rangeBV9Alarm_aux_temp_sens_out_of_rngeBV10Alarm_water_probe_miswiredBV11Alarm_water_probe_failedBV12Alarm_excess_fill_timeBV13Alarm_excess_refill_timeBV14Alarm_tank_not_drainingBV15Alarm_excess_water_no_demandBV16Alarm_no_SDU_airflowBV17Alarm_no_power_vent_airflowBV18Alarm_no_combustion_airflowBV19Alarm_blocked_flueBV20Alarm_burner_1_failedBV21Alarm_burner_2_failedBV22Alarm_burner_3_failedBV23Alarm_burner_4_failedBV24Alarm_ignition_module_1_failedBV25Alarm_ignition_module_2_failedBV26Alarm_ignition_module_3_failedBV27Alarm_ignition_module_4_failedBV28Alarm_blower_1_failedBV29Alarm_blower_2_failedBV30Alarm_blower_3_failedBV31Alarm_blower_4_failedBV32Alarm_gas_valve_1_failedBV33Alarm_gas_valve_2_failedBV34Alarm_gas_valve_3_failedBV35Alarm_gas_valve_4_failedBV36Alarm_low_waterBV37Alarm_foaming_fault_2BV38Message_replace_contactorsBV39Message_service_unitBV40Message_drain_pendingBV41Message_no_duct_airflowBV42Message_interlock_openBV43Message_freeze_prevent_drainingBV44Message_end-of-season_activeBV45Message_temp_comp_onBV46Message_clean_probesBV47Message_duct_HL_tripBV48Message_duct_HL_spanBV49Message_insufficient_waterBV50Message_boiling_temp_calibratedBV51Alarm_Current_Sense1_Out_Of_RangeBV52Alarm_Current_Sense2_Out_Of_RangeBV53Alarm_OvercurrentBV54Alarm_Supply_WaterBV55Alarm_Foaming_FaultBV56Message_Check_CylinderBV57Alarm_Overcurrent_2BV58Alarm_Supply_Water_2BV59Message_Check_Cylinder_2MV1Run_modeMV2MT_Runmode
Integration notes
- From Table 71-1 "Interoperability variable and object names" (object names are the "Variable name and BACnet object name" column) and Table 81-1 "Multi-tank fieldbus profiles" (names from its "BACnet description" column).
- Where several names share an instance (BI 6 GTS/STS, BI 8-9 single-tank vs multi-tank), the names are joined with " / ". BV 7 is printed with three names (RH, dew point and demand signal out of range); it is listed under the first and the others are in its description.
- Run_mode (MSV 1) and the AV 5-7 setpoints are printed as separate write and read rows and merged here.
- Units follow the I-P setting (SI: °C, kg/h, kg, bar). "100 lbs" is printed for the water-until objects.
- Multi-tank objects (AI 8-9, AV 14-15, MSV 2, and the MT names on BI 8-9) only apply in multi-tank mode.
- Newer controllers use Vapor-logic 6, which has a different (CamelCase) object list.
Check it against the live device. A points list tells you what the controller can expose; the unit in front of you may differ by firmware or installed options. This list is provided as-is for reference only and may contain mistakes — confirming it before you write, map or commission anything is up to you (terms). Easy BACnet scans a network for BACnet IP devices from an Android phone, reads every object on the Vapor-logic 4 and exports what it actually has to Excel — free. New to BACnet? Start with what a BACnet points list is and what the object types mean.
Questions about the DriSteem Vapor-logic 4
How many BACnet points does the DriSteem Vapor-logic 4 have?
This list has 100 BACnet objects: 11 analog inputs, 15 analog values, 11 binary inputs, 2 binary outputs, 59 binary values, 2 multi-state values. The exact set on a given unit depends on its firmware, installed options and configuration.
Which DriSteem Vapor-logic 4 BACnet points are writable?
69 of the 100 objects accept a write. Points marked Command have a priority array: a write holds until it is released, so release it back to automatic when you are done.
Where is the official DriSteem Vapor-logic 4 BACnet documentation?
The source is Vapor-logic4 Installation and Operation Manual (VL4-IOM-0312), revision 2012 (0312), published free by DriSteem at https://d2tsmyh31fn7w8.cloudfront.net/public-documents/docs/historical-literature/vl4_iom.pdf.
What are the minimum BACnet points to integrate the DriSteem Vapor-logic 4?
Start with MV 1 Run_mode (Run mode: 1 auto, 2/3 standby, 4 drain); AV 9 Fieldbus_demand_% (Demand from the BMS, % of capacity); AV 5 Space_RH_set_point (Space RH setpoint (unit controls)); BV 4 Clear_all_faults (Write 1 to clear faults); AI 1 Space_RH (Space RH); AV 2 Steam_output_percent (Estimated steam output, %); AI 5 Steam_demand_percent (Demand the unit is acting on, %); BV 3 Active_manually_cleared_alarms_exist (A manual-clear alarm exists).
How do I enable BMS control of the DriSteem Vapor-logic 4?
Run_mode (MSV 1) selects Auto, Local standby, System standby or Manual drain. The humidifier also needs its safety interlock and airflow inputs made (BI 1-3 show their state).
Can the BMS supply sensor values to the DriSteem Vapor-logic 4?
The space, dew point and duct RH values are read-only AIs from the unit's own transmitters; the BMS can send a demand (AV 8 mass or AV 9 percent, write-only) instead.
How do I check these points on the real Vapor-logic 4?
Scan the network with a BACnet IP browser such as Easy BACnet, open the device and compare its object list with this table. Anything missing is usually an option that isn't installed or a point that is disabled in the controller's configuration.
More DriSteem BACnet points lists
- Humidifier controller / humidistat (BACnet MS/TP)
DriSteem TRI2 BACnet humidistat
DriSteem model TRI2 room or duct humidistat with BACnet, controlling a DriSteem modulating humidifier (analog output) or a DriSteem dehumidifier (digital output).
Also known as: TRI2, DriSteem TRI2, TCI humidistat, DriSteem BACnet humidistat, X2 controller, AEX-BAC - Humidifier controller
DriSteem Vapor-logic 5
DriSteem Vapor-logic version 5 humidifier controllers (older generation before Vapor-logic 6) on GTS, STS, XT, Vaporstream, HPS and similar humidifiers.
Also known as: Vapor-logic5, Vapor-logic version 5, VL5, Vaporlogic 5, DriSteem humidifier controller (legacy) - Humidifier controller
DriSteem Vapor-logic 6
Vapor-logic version 6 controller used on DriSteem GTS, STS, XT, Vaporstream, HPS, LMH, Ultra-sorb XV and evaporative (WM) humidification systems.
Also known as: Vapor-logic, Vapor-logic version 6, VL6, Vaporlogic, DriSteem humidifier controller
Source: Vapor-logic4 Installation and Operation Manual · VL4-IOM-0312 · rev. 2012 (0312). Object names, instances and units are reproduced as published; descriptions are our own.