5 Minute read
| Overview
The 75F BMS (Building Management System) uses multiple sensors to monitor various environmental and operational parameters within a building. These sensors are typically wired to smart field devices such as SmartNode, HelioNode, SmartStat, and HyperStat.
The smart devices collect data from the connected sensors and may also measure additional onboard parameters. This field-level data is transmitted over the 900 MHz RF mesh network, which is managed by the CM (Control Mote).
The CM functions as the primary RF gateway in the system. It actively manages the 900 MHz mesh communication, including modulation type and transmission speed settings. The CM handles RF communication between smart devices and the CCU, ensuring reliable data exchange across the network.
The CCU (Central Control Unit) aggregates all field data received through the CM. It then transmits this aggregated data to the BMS applications (Facilisight and Internal Portals) via standard internet/cloud connectivity for monitoring and management by the facility team.
NOTE: Bluetooth is used only for device pairing and commissioning. Runtime operational communication between smart devices and the CCU occurs over the 900 MHz RF mesh network managed by the CM.
| Transmission Speed
The 75F system supports two transmission speed modes. These settings must be configured in both the CM (Control Mote) and the smart devices.
Transmission speed is a configurable option available in both the CM and the smart devices. This setting determines the RF communication rate over the 900 MHz mesh network between the CM and field devices. It does not affect the CCU’s internet connectivity or cloud data transfer rate to BMS applications.
The transmission speed configured in the CM must match the transmission speed configured in all associated smart devices to ensure proper RF communication.
Low Transmission Speed
The 'Low' transmission speed is the default mode where the transmission happens via the digital modulation technique BPSK Modulation, and the data is transmitted at a speed of 40 Kbit/ sec.
Medium Transmission Speed:
The 'Medium' transmission speed, where the transmission happens via digital modulation technique QPSK Modulation and the data is transmitted at a speed of 250 Kbit/ sec.
| Setting Transmission Speed in the CM
The Transmission speed type in the CM (Control Mote) is set using the two dip switches provided by the CM board.
Below are the steps to set the Transmission speed type in the CM board.
Remove the CCU tablet from the CM board.
- Locate the Dip switches provided to set the transmission speed type.
The Dip switches have two Positions “0” or “1” (Left is 0 /Right is 1. These two-minute white switches can be moved from left to right and right to left using a small pin screwdriver or fingernails.
By Default Mode, both switches are on the left, which is towards Position “0” and implies the CM is communicating in “Low” speed, where the transmission happens via digital modulation technique BPSK Modulation, and the data is transmitted at a speed of 40 Kbit/ sec.
Move both the switches to the right, which is towards Position “1”, to set the CM communication speed to “Medium" speed, where the transmission happens via digital modulation technique QPSK Modulation, and the data is transmitted at a speed of 250 Kbit/ sec.
Below is a table to illustrate the Dip switch positions and their corresponding descriptions of what the positions of the Dip switches mean.
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