DEV 1953, Руководство пользователя

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User Manual DEV 1953
108

Copyright DEV Systemtechnik GmbH 2015-2017

The
<checksum>
byte is calculated by a bit-by-bit eXclusive OR (XOR) operation
of all bytes in the record including header byte (
<STX>
,
<ACK>
, or
<NAK>
) and stop
character (
<ETX>
).

The
<negative_response>
byte indicates the detected type of error:
x
Checksum incorrect
The checksum received is detected to be different to the calculated checksum,
an example for this type of response
hexadecimal:
15 46 46 78 03 74
content:
<NAK> <address=FF> x <ETX> <checksum>
c
Command unrecognized
An unspecified command was received, an example for this type of response
hexadecimal:
15 43 30 63 03 1C
content:
<NAK> <address=C0> c <ETX> <checksum>
u
Command unavailable
A command was received which is not implemented or which cannot be
executed due to the current operation mode (Local Mode!) of the device,
an example for this type of response
hexadecimal:
15 31 31 75 03 79
content:
<NAK> <address=11> u <ETX> <checksum>
i
Improper data
A command with too few or too many bytes was received,
an example for this type of response
hexadecimal:
15 46 38 69 03 1B
content:
<NAK> <address=F8> i <ETX> <checksum>
d
Data out of range
A command was received with data bytes exceeding the range (e.g. of the
output port number or of the input port number) of the device,
an example for this type of response
hexadecimal:
15 30 31 64 03 69
content:
<NAK> <address=01> d <ETX> <checksum>

The switching command (
S
, chapter 5.8.3.5) can be only executed in
Remote Mode.