MULTI GAUGE CONTROLLER
COMMUNICATION
. . .
ENUMERATED, BOOL AND INTEGER PARAMETERS
These variables are always occupying one word in the memory. For variables smaller than: bytes,
the upper byte is illed with x value.
These variables are read via x
function, and they can be recorded via x
or x
function.
Remember to ill with x the upper byte (MSB) of variables smaller than bytes during writing.
. . .
FLOAT TYPE
The format is compatible with the IEEE-
standard and is used in almost every programming lan-
guage of higher level such as C, C++. In addition, most of automatics equipment or built-in systems
allows for their automatic decoding.
Variables written in this format are organised as -byte data in two consecutive table word in the
“MSB irst” order. Writing and reading of these variables is possible only via x
and x
com-
mands. An attempt to write or read such variable in half will be discarded and an error message
will be generated.
Note that in practice, when using C, IEEE loats may usually be decoded by
placing the values returned over comms into memory and ‘casting’ the region
as a loat, although some compilers may require that the area be byte swapped
high to low before casting (e.g. MSB B B LSB →LSB B B MSB).
MODBUS ADDRESS
MODBUS A
MSB
LSB
MSB
LSB
Bits
-
Bits
-
Bits
-
Bits -
Table . : Float IEEE-
format in Modbus table
For example, to transfer the value .
, the following values are transmitted (hexadecimal):
MODBUS ADDRESS
MODBUS A
MSB
LSB
MSB
LSB
x F
x
x
xC
Table . : Example loat IEEE-
value in Modbus table
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