EIA-232 Communication
BMTW-SVN01F-EN 173
Configuring a BACnet-Compatible Device
A BACnet-compatible device that communicates using an EIA-232 con-
nection with the BCU must meet the following parameters:
• Communication at 9,600 baud
• 8 data bits, 1 stop bit, no parity
• Cable connection to the DB-9 or DB-25 connector on the EIA-232
interface card in the BCU
Specifications for EIA-232 Cable Connections
Table 33 provides specifications for the EIA-232 cable used to connect the
BCU to a BACnet-compatible device.
DB-9 Pin Assignments
Figure 81 provides the DB-9 pin assignments for a BACnet device and a
Tracer Summit BCU.
Figure 81: DB-9 connector cable pin connections
Table 33: EIA-232 cable specifications
Specification Description
Length 50 feet (15.24 meters) maximum
For longer distances use a short haul modem.
Shield Shield the cable to comply with FCC regulations and
to protect the BCU from electrical noise.
EIA-232 card with 9-pin
male connector
Pin 3 = Transmit data (output)
Pin 2 = Receive data (input)
Pin 5 = Signal ground
Pin 1 = DCD
Com = 1
Pin 7 = RTS
IRQ = 4
Receive data pin assignment (input)
Transmit data pin assignment (output)
Signal ground pin assignment
Jumpered
BACnet device
Tracer Summit BCU
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