Communication
The communication to the CCTHV-407 is done using BACnet MSTP protocol on a RS-485 physical link. The BACnet network allows the reading of the thermostat states and the writing of new setpoints and configurations.
Network Characteristics
When the CCTHV-407 thermostat is at one end of a RS-485 network, we may enable the terminating resistor by installing JP1 (supplied) to end the network or use an external resistor. (Call Cristal Controls for model number and order)
For more information, refer to the Cristal Controls manual "Setting up a RS-485 Network".
Objects
Next is the BACnet objects list. This list is simple and many objects allow direct control on inputs and outputs of the thermostat.
| Object | Instance | Name | Min Value | Max Value | Default | Description | Notes |
|---|---|---|---|---|---|---|---|
| Device | CCTHV-407-BAC | 0 | 4194302 | ||||
| BI | 0 | DIGITAL IN 1 | 0 = OFF | 1 = ON | Digital input DI 1 | ||
| BI | 1 | DIGITAL IN 2 | 0 = OFF | 1 = ON | Digital input DI 2 | ||
| BO | 0 | RELAY AU | 0 = OFF | 1 = ON | 0 = OFF | Auxiliary Relay "AU" | 3 |
| BO | 1 | RELAY G | 0 = OFF | 1 = ON | 0 = OFF | Fan Relay "G" | 3 |
| BO | 2 | RELAY Y1 | 0 = OFF | 1 = ON | 0 = OFF | Cooling Relay "Y1" | 3 |
| BO | 3 | RELAY Y2 | 0 = OFF | 1 = ON | 0 = OFF | Cooling Relay "Y2" | 3 |
| BV | 0 | OCCUPIED MODE | 0 = UNOCCUPIED | 1 = OCCUPIED | 1 = OCC | Occupied mode. Will allow thermostat to change the setpoint. | |
| BV | 1 | FAN STATUS | 0 = OFF | 1 = ON | 0 = OFF | Fan Relay state feedback | |
| AI | 0 | TEMPERATURE INT | -327.6°C | 327.6°C | On-board internal 10K temperature sensor. | ||
| AI | 1 | TEMPERATURE REM | -327.6°C | 327.6°C | Optional remote 10K temperature sensor. | ||
| AI | 2 | INPUT 0-10V | 0.0% | 100.0% | From 0-10 Volts DC analog input "0-10_In". | ||
| AI | 3 | TEMPERATURE 0-10V | -3276.7°C | 819.0°C | Optional 0-10V temperature sensor. | ||
| AO | 0 | TRIAC W1 | 0.0% | 100.0% | 0.0% | Heating Triac "W1". Value will pulse at 1 Hz. | 3 |
| AO | 1 | TRIAC W2 | 0.0% | 100.0% | 0.0% | Heating Triac "W2". Value will pulse at 1 Hz. | 3 |
| AO | 2 | OUTPUT 0-10V | 0.0% | 100.0% | 0.0% | 0-10 Volts DC analog output "0-10_Out". | 3 |
| AV | 0 | OFFSET INT | -10.0°C | 10.0°C | 0.0°C | Internal temperature calibration. | 4 |
| AV | 1 | OFFSET REM | -10.0°C | 10.0°C | 2.4°C | External temperature calibration. | 4 |
| AV | 9 | SETPOINT HEAT | -327.0°C | 327.0°C | 20.0°C | Temperature setpoint for heating. | 2, 6, 7 |
| AV | 10 | SETPOINT COOL | -327.0°C | 327.0°C | 22.0°C | Temperature setpoint for cooling. | 2, 6, 7 |
| AV | 2 | SETPOINT HEAT UNOCC | -327.0°C | 327.0°C | 18.0°C | Unoccupied temperature setpoint for heating. | 1, 4, 6, 7 |
| AV | 3 | SETPOINT COOL UNOCC | -327.0°C | 327.0°C | 25.0°C | Unoccupied temperature setpoint for cooling. | 1, 4, 6, 7 |
| AV | 4 | SETPOINT MIN | 10.0°C | 70.0°C | 15.0°C | Minimum temperature setpoint adjustable on the thermostat. | 4 |
| AV | 5 | SETPOINT MAX | 10.0°C | 70.0°C | 25.0°C | Maximum temperature setpoint adjustable on the thermostat. | 4 |
| AV | 6 | HEATING STATUS | 0.0% | 100.0% | 0.0% | Heating status of the thermostat, output independent. | 4, 6 |
| AV | 7 | COOLING STATUS | 0.0% | 100.0% | 0.0% | Cooling status of the thermostat, output independent. | 4, 6 |
| AV | 8 | POWER LIMIT | 0.0% | 100.0% | 100.0% | Allowed maximum value for the outputs. 0% = Full Shedding. | 4 |
| AV | 11 | SETPOINT HEAT LIMIT | -99.0°C | 99.0°C | 99.0°C | Disable shedding if temperature fall below this limit. | 1, 4, 8 |
| AV | 12 | SETPOINT COOL LIMIT | -99.0°C | 99.0°C | -99.0°C | Disable shedding if temperature increase over this limit. | 1, 4, 8 |
| AV | 13 | TEMPERATURE 0-10V MIN | -3276.0°C | 3276.0°C | -50.0°C | Minimal value in °C for the 0-10V input. Value in °C corresponding to 0V. | |
| AV | 14 | TEMPERATURE 0-10V MAX | -3276.0°C | 3276.0°C | 50.0°C | Maximal value in °C for the 0-10V input. Value in °C corresponding to 10V. | |
| MSV | 0 | HVAC MODE | 1 | 6 | 1 | System operating mode selection. | 9 |
| MSV | 1 | FAN MODE | 1 | 5 | 2 | Fan mode behavior adjustment. | 5 |
| FILE | 0 | Config.bin | - | - | - | Thermostat configuration file |
Notes:
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Negative values will be relative to the occupied setpoint.
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User setpoint adjustment from thermostat write at a configurable priority in the "Settings" tab of the software "BACnet Browser" (see the "Settings" tab).
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The thermostat writes the object at a configurable priority in the "Settings" tab of the software "BACnet Browser" (see the "Settings" tab).
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No priority
-
Mode definition: "On" : always enable, "Auto": enable when heating or cooling, "Fan Cool": stay enable when last active stage was a cooling stage, "Fan Heat": stay enable when last active stage was a heating stage, "As schedule": enable when occupancy mode is occupied, "Auto" otherwise.
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When no heating stages are configured, the "Reliability" properties of the objects linked to heating take the "No Output" value. Same thing happens to objects linked to cooling when no cooling stages are configured.
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Using the 0-10V temperature input, the minimum and maximum values depend on the objects "TEMPERATURE 0-10V MIN" and "TEMPERATURE 0-10V MAX".
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Temperature setpoints less comfortable than the occupied setpoint are ignored.
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State definition: 1 = "Auto": enable heating and cooling, 2 = "Heat": heating only, 3 = "Cool": cooling only, 4 = "Emergency Heat": emergency heat stage, 5 = "Fan": fan only, no heating or cooling, 6 = "Off": all stages disabled.
Proprietary Properties
In addition to the standard BACnet properties, the Device object exposes vendor proprietary properties.
| Property ID | Name | Type | Access | Default | Description |
|---|---|---|---|---|---|
| 512 | MAC ADDRESS | Unsigned | Read / Write | MSTP MAC address of the thermostat on the RS-485 network. Writable range 0 to 254. | |
| 513 | BAUDRATE | Unsigned | Read / Write | 2 = 38400 | RS-485 baud rate index: 0 = 9600, 1 = 19200, 2 = 38400, 3 = 57600, 4 = 76800, 5 = 115200, 6 = 230400. |
| 901 | SYSTEM INFO TEMPERATURE | Real | Read only | Temperature in degree celcius measured by the on-board microcontroller sensor. | |
| 903 | SYSTEM INFO UPTIME | Unsigned | Read only | Elapsed time in seconds since the last device restart. |