HBM ML71BS6, Руководство по эксплуатации

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14 MGCplus−ML71BS6
A0851-3.1 en HBM
6 CAN protocol
Up to 128 measured values can be transmitted at each bus.
A number of signals is assigned to each bus. This determines the signal
transmission rate at the particular CAN port (in the case of CAN port 2, the
operating mode of CAN port 1 is also a factor).
6.1 Measurement signal transmission
The operating priority for the two CAN ports is different. CAN port 1 always
takes priority, to ensure that the transmission pattern of the data sent from
here is exactly periodic. When sending a synch signal, the values sent thus
far are valid here. CAN port 2 has the lower priority. Measurement signals can
be transmitted in the following three formats.
6.1.1 Absolute values in Float
In each 8−byte CAN message, 2 signals are transmitted as Float values
(32−bit). This is dealing with scaled measured values.
6.1.2 In digits as Long
In each CAN message, 2 of these values are transmitted as Long (32-bit),
with the MSByte
1)
always being 0. Digital value scaling can be preset by using
two point calibrations.
6.1.3 In digits as Word
In each CAN message, 4 of these values are transmitted as Words (16-bit).
Digital value scaling can be preset by using two point calibrations.
6.1.4 Identifier assignment
Default assignment
The possible formats are sent out for the same signal under different
identifiers, so that fixed scaling can be assigned in the receiver of a specific
ID. The synch message at
CAN port 1 has the identifier 80h
2)
and does not contain any data bytes.
1)
Most significant byte
2)
This hexadecimal number corresponds to the decimal value 128