Aalborg DFC Digital User Manual

Page 34

APPENDIX 4

SENDING COMMANDS TO THE DFC

RS485

The standard DFC comes with an RS485 interface. The protocol described below
allows for the unit using either a custom software program or a “dumb terminal”.
All values are sent as printable ASCII characters. The start character is always !and
the command string is terminated with a carriage return (line feeds are
automatically stripped out by the DFC:

!, ,Arg1,Arg2,Arg3,Arg4

WHERE:

Start character

Addr

RS485 device address in the ASCII representation of
hexadecimal (00 through FF are valid).**

Cmd

The one or two character command from the table above.

Arg1 to Arg4

The command arguments from the table above.
Multiple arguments are comma delimited.

Carriage return character.

Default address for all units is 11.

Several examples of commands follow.
All assume that the DFC has been configured for address 15 (0F hex) on the RS485 bus:

To put the unit in digital mode:

!0F,M,D

The DFC will reply:

!0FMD

To set the flow of 50% of FS:

!0F,S,50.0

The DFC will reply:

!0FS50.0

To get a flow reading:

!0F,F

The DFC will reply:

!0F50.0
(Assuming the flow is at 50% FS)

Set the high alarm limit to 5% above Set point:

!0F,A,H,5.0

The DFC will reply:

!0FA5.0