Me GSV-4, Operating Instructions Manual

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CAN bus
Devices with CAN bus have the same command structure as devices with serial interfaces
or Bluetooth or GPRS. Prefixes and postfixes are omitted if the measured values and
responses are sent within a CAN bus frame.
Protocol for measured values
Measured values via CAN are always transmitted in a CANbus frame. Bytes 1 to 8 include
the measurement data of the 4 channels with 16 bit each. First the highbyte (HB) and then
the lowbyte (LB) is sent.
Channel 1 Channel 2 Channel 3 Channel 4
HB LB HB LB HB LB HB LB
Table 11: CAN frame with measurement data;
Protocol for commands
Commands begin with the code followed by parameters.
Code Parameter
xx p1 p2 ... pn
Examples:
Requesting serial number 1F
Setting channel 1 to zero: 0C 01
Protocol for responding to commands
Commands for the measuring amplifier are transmitted in the CAN frame (data range). If the
measuring amplifier sends a response, a command response frame is sent.
Head frame:
Prefix Code n len No.
3B xx B HB LB aa bb cc
Table 12: Head frame for responding to commands via CAN bus
Frame 1 ... n
B B B B B B B B
B B B B B B B B
...
...
B B B B B B B B
Table 13: Following frame for responding to commands via CAN bus
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