SA Bus Device Limits - BCPro - LIT-12011908 - General System Information - BCPro System - 4.0

MS/TP Communications Bus for the BCPro System Technical Bulletin
Product
Building Automation Systems > Building Automation Systems > BCPro System
Document type
Technical Bulletin
Document number
LIT-12011908
Version
4.0
Revision date
2020-03-16

The SA Bus is limited to 10 devices total to ensure good communication on the bus and is limited to four NS sensors because only four unique addresses can be set on the sensors. Due to change of value (COV) limitations, it is best to limit the number of CH-PCXs on the SA Bus to four. The SA bus is also limited by the total power consumption of the devices connected on the bus. Exceeding the total power consumption limit can cause poor bus communication and cause devices to go offline.

Table 1 provides the power consumption of devices commonly connected to the SA bus.
Important: The total power consumption for the SA Bus is limited to 210 mA on the SA Bus modular jack and 240 mA on the SA Bus terminal block. Exceeding the total power consumption limit can cause poor bus communication and cause devices to go offline.

Table 1. Power Consumption by Common SA Bus Devices

SA Bus Device

Power Consumption on the SA Bus

Discharge Air Sensors (NS-DTN70x3-0)

12 mA

Balancing Sensors (NS-ATV7003-0)

25 mA

Network Sensors without display

13 mA

Network Sensors with display no RH

21 mA

Network Sensors with display and RH

27 mA

CO2 Network Sensors (NS-BCN7004-0)

28 mA (non-isolated) or 5 mA (isolated)

Variable Speed Drives

NA (self-powered)

CH-PCX Series Controllers

NA (self-powered)

SA bus applications are limited to a power load of 210 mA (SA Bus modular jack) or 240 mA (SA Bus terminal block).