ABB AnalyzeIT ZMT Series Ergänzende Betriebsanleitung - Seite 17

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A2 Non-volatile Memory Limitations

Note. A non-volatile memory is used to store any
parameter changes made via the serial link to ensure that
the information is retained during mains interruption or
power-down. The memory used is rated at 10
per register and each register is assigned a particular
parameter, e.g. Alarm set point value. If the number of
write cycles to any particular register exceeds this value,
the register's contents may not be retained.

A3 Block Check Characters

The block check character (BCC) transmitted is determined by
the seven least significant bits in the binary arithmetic sum of a
complete message (excluding parity bits). All characters
transmitted before the BCC must be included in the arithmetic
sum. Refer to Appendix A1 for ASCII characters.

A3.1 BCC Example

Message – STXR01A1ETX
Find the ASCII decimal equivalent of each character in the
message, calculate the decimal arithmetic sum and hence
obtain the binary arithmetic sum.
STX
=
2
R
=
82
0
=
48
1
=
49
A
=
65
1
=
49
ETX
=
3
Only the seven least significant bits (LSB) of the binary
arithmetic sum are required to determine the BCC:
MSB
LSB
10 0101010
*
'
' is the BCC transmitted –
see Appendix A1
4
write cycles
Arithmetic sum =
298 decimal
100101010 binary
APPENDICES...
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