4. POWER AND RS485 CONNECTIONS
Device connections to gateway
Gateway 6 Pin Phoenix connector for RS-485 Devices:
- Pins 1 through 3 are for RS-485 devices (Use standard grounding principles for RS-485 GND).
- Pins 4 through 6 are for power.
NOTE: Do not connect power until next chapter.
Power-Up gateway
BACnet MS/TP: Wiring field port to RS-485 Network
Connect the BACnet MS/TP RS-485 network wires to the 3-pins RS-485 connector on gateway
as shown below (use standard grounding principles for RS-485 GND):
Pins
Device Pins
Gateway Pins
1
Pin RS-485 +
B +
2
Pin RS-485 -
A -
3
Pin GND
SG
4
Power In (+)
PWR +
5
Power In (-)
PWR -
6
Frame Ground
FG
Pins
Device Pins
Gateway Pins
1
Pin RS-485 +
+
2
Pin RS-485 -
-
3
Pin RS-485 GND
G
Check power requirements in the table below:
See the section 5 for information on connectiong to BACnet/IP network.
Power Requirement for gateway External
Current Draw Type
Gateway Family
12V DC/AC
24V DC/AC
30V DC
FPC – N34 (Typical)
170mA
100mA
80mA
FPC – N34 (Maximum)
240mA
140mA
100mA
NOTE: These values are ‘nominal’ and a safety margin should be added to the
power supply of the host system. A safety margin of 25% is recommended.
NOTE: When setting DIP switches, ensure that power to the board is OFF
Apply power to gateway as shown below. Ensure that the power supply used complies with the specifications provided in chapter 1.
- Gateway accepts either 9-30V DC or 12-24V AC on pins 4 and 5.
- Frame GND should be connected.
5
Auto-Discovery: After completion - Turn Off to save configuration
NOTE: if Modbus TCP/IP was selected for the field/BMS protocol, skip this section.
Auto-Discovery is not used for MODBUS TCP/IP.
The S3 DIP Switch for enabling Auto-Discovery should have been set in the previous chapter before applying power to the gateway.
NOTE: Do not enable Auto-Discovery when the unit is powered.
When power is applied to a gateway that is set to enable Auto-Discovery, it will take about 3 minutes to complete the discovery of all the RS-485
attached to the gateway (the “TX” led will flash during the Auto-Discovery). Once completed, the “TX” and “RX” leds should flash rapidly, indicating
good communication between discovered devices.
Once the gateway has discovered all the RS485 devices, set the S3 DIP switch to the OFF position to save the current configuration.
S3 DIP Switch Auto-Discovery Mode
S3
Auto-Discovery ON - Build New Configuration
On
Auto-Discovery OFF - Save current Configuration
Off
