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BACnet is an open Communication Protocol that was developed by ASHRAE (American Society of Heating, Refrigerating, and Air-Conditioning Engineers).
This is a link to the BACnet Website: http://www.bacnet.org/index.html
Schneider Electric Drives support only the MS/TP version of BACnet. MS/TP stands for Master-Slave/Token-Passing. This is a 2-wire RS485 based network protocol, similar to ModBus.
Other vendors may support BACnet over Ethernet and Arcnet. (don’t be surprised if we do offer an Ethernet option in the future).
Usually the BACnet Master (controller) communicates to several different routers or bridges over Ethernet (called BACnet IP) or ArcNet, and these devices are connected via the 2 wire RS485 hardwire connection to our drives.
ATV212 implementation of BACnet:
Embedded BACnet communications (ModBus, Apogee P1, Metasys N2, and BACnet).
Lonworks option available (Part Number VW3A21212)
A is –
GND is Ground (actually signal common)
B is +
SCR is Shield
Programming in the Drive:
F829 (Network Protocol): Set to 4 for BACnet Communications
F890 (Network Address): Set the network address from 0 to 127.
F891 (Network Baud Rate): Sets the speed of communication between the drive and the master. Options are AUTO, 9600, 19200, 38400, and 76800. Default is AUTO. All devices on the RS485 network must communicate at the same Baud Rate.
Format: This is fixed at 8-N-1. Stands for 8 Data bits, No Parity, and 1 Stop bit. All devices on the RS485 network must be set to the same format.
F892 (Network Time-Out): Adjustable between 2 to 60.0 seconds (20 to 600 tenths). Sets the time before the drive will “Time Out” indicating a loss of communication with the controller.
F893 and F894 (Instance Number): F893 is adjustable between 0 and 4194. F894 is adjustable between 0 and 999.
Example: If F893 is 0235 and F894 is 0045 the Instance number is 0235045.
This must be unique for each device on the network, and we recommend it be set higher than the Address. This is also known as the BACnet device ID.
F895 (Max Master): Adjustable between 0 and 127. Sets the Maximum number of devices allowed on the network. Reducing this number can improve network speed and data through put.
F896 (Max Info Frames): Adjustable between 1 and 100. Sets the time period (# of Frames) that the drive “owns” the Token. Lower numbers will increase network speed, but may not allow the drive to update all parameters on one scan. Higher numbers will allow full data transfer, but slower update times. Factory default is 1. We recommend this be set to 10.
FA15 (Communication Counter): Read Only. Displays the total number of Frames received by the drive sine the last power on. If this number is very low, or not increasing, then it indicates network problems.
FA16 (Normal Communication Counter): Read Only. Displays the number of bad frames received since the last power on. If this number is High or increasing rapidly it indicates network problems.
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