Festo SFC-DC series, Manual

Page: 155 / 202

B. Supplementary information
B−13
Festo P.BE−SFC−DC−IO−EN en 0801a
Please note
Direct transfer of values via the serial interface with CI
commands always takes place in the basis system and
assumes there is a conversion to increments.
All parameters are always saved in increments in the con
troller and are not converted into the relevant measuring
system until they are written in or read out. All physical
variables (position, speed and acceleration) must be con
verted into increment values before they can be trans
ferred.
Further information on converting can be found in appen
dixB.6.
All values are transferred in hexadecimal figures; 1 character
represents 4 bits; it is known as a tetrad <Tn>. The first tetrad
transferred contains the higher−value bits of the value. Gen
eral information: Tetrad <Tn> contains the bits b
n
...b
n+3
.
Example:
UINT8
Dec 26
Hex
1 O
Bin 0 0 0 1 1 0 0 0
b
7
b
6
b
5
b
4
b
3
b
2
b
1
b
0
Tetrad T
4
Tetrad T
0
Checksum <PS> The checksum is formed from the sum of all sent bytes and
shortened to 1 byte (modulo 256).
The other station must compare the sent command with the
echo" of the controller and process the checksum.
Checksum
Syntax IIIISS:<Checksum>
Format 2 hexadecimal figures
Type UINT8