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BACNet Flow CoNtroller
MAINTENANCE
troubleshooting
Fault
Binary Outputs not functioning
Analog Outputs not functioning
BACnet Communication Errors
26
BACNet FLow CoNtroLLer - Manual | priceindustries.com
Solution
The Binary outputs send out 24VAC and are factory wired to the LED on the FFU. Make sure the BFC has
24VAC power, and then check voltage at binary outputs and COM terminals if the LED does not light up.
The Analog outputs send out 0-10VDC. Make sure the BFC has 24VAC power, and then check voltage at
the suspect analog output with a multimeter. You should see a voltage range of 0-10VDC.
Option #1
BACnet - MS/TP is based on a RS-485 network. It must be wired in a daisy chain configuration. A daisy
chain means that there is only one main cable, and every network device is connected directly along its path.
DO NOT use Star, Bus, "T", or any other type of network configuration. Any of these other network
configurations will result in an unreliable network, and make troubleshooting almost impossible.
Correct polarity is imperative on MSTP wiring. Always ensure that the positive terminal on a device has
the same color wire connected to it throughout the network, same for the negative terminal.Eg. 2 wire
conductor with black and white wires – black to the positive terminal, and white to the negative terminal.
Keep this consistency throughout the network.
Option #2
Price does not use EOL or termination on their devices. Terminating a device is almost never required
at the low baud rate of MS/TP devices. In fact terminating can create more problems than it solves.
The network speed or baud rate must be the same throughout the network.
Note:
The default speed for Price BACnet MS/TP controls is 76800. BACnet MS/TP currently supports
4 standard speeds which are: 9600, 19200, 38400 and 76800.
Option #3
Binary Address must be unique for each device on the network. No two devices can have the same
Address. This includes if you are incorporating a Price product into an existing network. Determine
the existing Addressing scheme for the existing network. The Address is set on the Addressable dip
switches on the UMCB.
Option #4
Grounding and 24VAC polarity: Proper grounding is absolutely essential when wiring the MS/TP
BACnet Network. Proper grounding will prevent many potential problems that can occur in a network
of devices. Common symptoms of a poorly grounded network can include inconsistent BACnet MS/
TP communications and damage from voltage spikes. The most practical method of grounding is to
ground every 24VAC transformer common/neutral used to power the controls.
Connect the "common/neutral" wire of the SECONDARY side of the transformer to earth ground –
such as the ground screw on in the electrical box.
Option #5
Note:
Flipping 24VAC HOT and COMMON will cause the BACnet MS/TP Network to stop
communicating!!! Ensure HOT and COMMON are not reversed on ANY controllers.
wArNING:
Controllers will still power up and run even if HOT and COMMON are reversed. However
output signals to other devices such as heaters, relays, etc will not work as intended!
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