Modbus Configuration; Addressing - Lochinvar Knight 81 Instructions Manual

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ModBus Confi guration
Th e ModBus communication board is equipped with a set of ten dip switches that are used to set the board confi guration
(address, baud rate, and parity settings). Th e fi rst eight are used to set the address of each board. Th e ninth is baud rate. Th e
tenth is parity.
Figure 3-1_ModBus Communication Board

Addressing

Th e ModBus addressing space is comprised of 256 diff erent
addresses.
• 0 is reserved for broadcast messages from the master
device
• 1 - 247 are free to use for each unique device
• 248 - 255 are reserved
To set the ModBus address the dip switches can be set in
either the 0 position or the 1 position. For switches set to
the 1 position their value will be added together to determine
the address.
Each switch set to the 1 position has the following value:
Dip switch 1 = 1
Dip switch 2 = 2
Dip switch 3 = 4
Dip switch 4 = 8
Dip switch 5 = 16
Dip switch 6 = 32
Dip switch 7 = 64
Dip switch 8 = 128
Any dip switch set to 0 has a value equal to 0.
ModBus and BACnet Communication Instructions
Example:
To set the address of the ModBus board to 50, dip switches 2, 5,
and 6 have to be set to the 1 position. Th e address is determined
by adding the values of all the dip switches together.
Address = Value of Dip switch 1 + Value of Dip switch 2 +
Value of Dip switch 3 + Value of Dip switch 4 + Value of Dip
switch 5 + Value of Dip switch 6 + Value of Dip switch 7 +
Value of Dip switch 8
In this example:
Address = 0 + 2 + 0 + 0 + 16 + 32 + 0 + 0 = 50
DIP SWITCHES
LED'S
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