BMS INTEGRATION

Information for Project Planners and Controls Engineers on Integration
of Turntide's Smart Motor System into an Existing BMS System.

Turntide motor controllers and supervisors can be integrated into third party BAS communication networks if existing systems support BACnet and/or Modbus communication protocols.

Modbus Motor Controller Integration

CAUTION!! If a motor controller is integrated into a BAS via Modbus cloud connectivity and the ability to update firmware and flows remotely is disabled. 

The motor controller can be integrated into a system without a supervisor if the existing system supports Modbus communication protocol. An integrator would need to reference the Modbus registers detailed in this document to establish point monitoring and control.

The Turntide motor system can be controlled from a master device via serial communications using the Modbus protocol direct to the Turntide motor controller. Holding registers are used exclusively in the controller making them Read/Write by definition. They are used as either writeable registers for the purpose of manual control inputs or read only for transmitting status values of parameter functions.

 

An isolated 2-wire RS485 Modbus RTU interface is used to communicate with the controller. The default setting is 19200 Baud; 8 data bits; 1 stop bit and Even Parity. These settings can be changed to meet a local requirement by using the procedure shown below.

 

For using a lower baud rate such as 9600, the suggested read approach is to do a group of qty 35 registers at one time which is more “efficient” and requires less bandwidth. After a group read is performed, the individual registers desired can be pulled out from the group read and registers not needed can be ignored. Multiple group reads can be performed until all desired registers are read.

 

Turntide motor controllers have a unique Modbus device address that can be configured between #1 to #10 with current production. Additional address locations can be opened to offer the full standard range of #1 to #247 upon customer request. The device number is automatically assigned when operated with the SMC Supervisor OR it can be manually pre-set as desired with the Turntide desktop app.

 

Application note for writing to the requested motor speed registers, 40133:40134. The requested motor speed is a 32-bit representation with LOW WORD in register 40133 and HIGH WORD in register 40134. This must be written as a ranged write with LOW WORD first followed by HIGH WORD. The HIGH WORD must be written although it will currently always be zero since Turntide motors are not specified at this time to run at speeds requiring the HIGH WORD bits.

Procedure for Setting Baud Rate, Data Bits, Stop, Start, Parity etc.

Note: Making changes to the default configuration settings can be performed by Turntide prior to shipment OR can be done by the user and will require the Turntide UI desktop software application and Modbus communication connection to your PC.

 

  1. Open Turntide UI and select the Motor Controller option

  2. Select USB as the connection mode

  3. Once connected to the Motor Controller, click the Gear icon to open the connection settings dialog

  4. Select the Edit button to make changes to the Baud Rate or Parity settings

  5. Select the preferred Baud Rate and/or Parity from the drop list

  6. Click Set to commit changes

  7. After making changes, it will be necessary to update the USB Settings to match the new Motor Controller communication parameters

 

Read-only Modbus status registers used for integration with third-party BMS Systems

2.3 - Motor Speeds

For each of the five modes, you can enter a different speed for the existing and Turntide motors on the ‘Input’ tab in rows 71 to 75. These speeds will apply for all 10 of the HVAC systems. For constant speed applications, set all modes to 100% speed. Reference speeds for RTUs are provided. If necessary, using rows 79 to 94, you can override each HVAC system to assign it its own unique speeds.   

For RTU and AHU fan systems, you must select whether the fan is set to ‘ON’ vs ‘AUTO’ mode. These selections determine the fan operation during ‘Vent’ mode. ‘ON’ means the supply fan runs during occupied times even when neither heating or cooling is operating to provide ventilation. RTUs without outdoor air dampers will typically be set to ‘Fan AUTO’ mode, meaning the fan only turns on during heating or cooling operation. 

While building codes mandate that commercial and industrial spaces use ‘ON’ mode during occupied times for RTUs with outdoor air dampers, per ASHRAE Standard 62.1, in practice it is common to find buildings that run their RTUs in ‘Fan AUTO’ during occupied times to reduce comfort complaints. This behavior is particularly prevalent in colder climates where employees and customers become uncomfortable from cold outdoor air falling on them while the RTU is not in heating mode. Moreover, a multitude of research studies evaluating RTU outdoor dampers found that the failure rate of outdoor dampers due to some issue (broken actuator, unplugged, excessive corrosion preventing actuation) ranged from 43% to 100% of the RTUs evaluated in each respective study (ACEEE 2014 publication). Consequently, the outdoor air damper should be investigated in addition to ensuring the fan control is ‘ON’ if the RTU provides ventilation to the space.

3 - 8760 Model

BMS Table 1.png

Digital Value Bits

Mapping of status bits for digital inputs and outputs.  Ignore bit positions not physically present on device.

BMS Table 3.png

Manual Mode Control

Writeable registers used to control motor operation in "Manual Mode" as used by Supervisor and Desktop App.

Figure 2.png

The table inside Figure 1 above summarizes the annual hours spent in each of the five RTU modes. For non-RTU systems, the annual hours and percent time spent in each mode can be overridden in rows 108 to 126 in the ‘Input’ tab. When overriding the 8760 model, we recommend acquiring BAS trend data from the building which will reveal hours spent in each mode with respect to the outdoor temperature. This trend data can be easily extrapolated to capture the annualized time in each mode.

BMS Table 2.png

Bacnet Integration

The supervisor or motor controller can be integrated into a system that supports BACnet communication protocol. The RJ-45 connection on the supervisor can be used to connect to a system via BACnet IP.  The motor controller can connect via Bacnet IP over a 2.4GHz wireless network.  Typical installations using the Tridium Niagara platform follow:

Niagara JACE to Supervisor via BACnet IP

Connect JACE RJ45 port and supervisor RJ45 port to a network switch via Ethernet cable. The Turntide Supervisor is connected to the motor controller via WiFi. Device must be manually defined with the appropriate configuration. The JACE will not auto-discover the supervisor as a BACnet device on the network. Once defined, the supervisor pulls into the network. All defined AVs, BVs and IO can be discovered with descriptions attached. Real time monitoring of both the supervisor and motor controller in this configuration is seamless provided the Cascade flows are configured to provide the desired data as well as for control of the motor controller through the supervisor. If BACnet integration is desired and cloud monitoring is allowed this is an ideal configuration.

 

Niagara JACE to Motor Controller via BACnet IP over WiFi

The JACE is connected to the network via Ethernet, the Turntide motor controller on the same network via WiFi (2.4GHz only).  Device must be manually defined with the appropriate configuration. The JACE will not auto-discover the motor controller as a BACnet device on the network. Once defined, the motor controller pulls into the network. A short list of predefined AVs and BVs will discover with descriptions intact. All AVs and BVs defined with Cascade will discover without attached descriptions. Real time monitoring and control of the motor controller are available once the database is built.