Schambeck SDS 9414I, Operation Manual, Page: 40 / 45

SDS 9414i HPLC Pump
Version: 2.2 (July 2007) Page: 40 / 45
After the “ * ” answer, the actual command is sent. The complete structure is outlined below:
Byte 1 Length This states the total length of the command,
including the checksum byte and its own length.
Normally, all commands have a length of 6 bytes.
Byte 2 Command Code This states the command to be executed. This can
be either a “
11 ” for setting a new flow, or a “ 10 ” for
synchronizing a command (see below).
Byte 3 Remote This byte can be either “ 80 ” for starting the pump, or
a “ 00 ” for stopping it.
Byte 4+5 Flow Rate These two bytes set the flow rate of the pump. The
value is scaled from 0x0000 to 0x0C80, where
0xC80 is equal to the highest possible flow rate,
depending on installed pump head (e.g. 4, 10, or 40
ml/min).
Byte 6 Checksum This is the checksum of the total command. It is
calculated as follows:
- add up all command bytes (Byte 1 to 5, except
checksum)
- the calculate the modulo 256 of the sum, add 1
and invert it.
The checksum added to all single bytes should
result in a value of 0.
Picture 10: Checksum Formula
Every command has to be finished with a “ ; ” after the checksum byte.