Specification; Appendices; A1 Non-Volatile Memory Limitations - ABB 4620 User Manual

12 SPECIFICATION

The specification for each instrument is as detailed in the
Operating Instructions for the instrument (see Section 1), with
the following additions:
EIA Communication
Standards
Parity
Transmission line length
Transmission speeds
24
RS422, RS485
2-wire or 4-wire modes
None
Odd Programmable
Even
1200m max.
1200 baud
2400 baud
Programmable
4800 baud
9600 baud

APPENDICES

A1 Non-volatile Memory Limitations

Note. If the number of write cycles to any particular
non-volatile memory register exceeds 10
register's contents may not be retained.
Any changes made to a parameter, e.g. Alarm trip value, via
the serial link are stored in a non-volatile memory register
assigned to that parameter.
The number of write cycles to a particular register can be
reduced by disabling the non-volatile memory access when
making changes to parameters which do not need to be saved
on power-down. This is done by using the
.
state (coil number 50)
When the
non-volatile save state
parameter changes made via the serial link are written to the
non-volatile memory register and retained on power-down. If
the
non-volatile save state
changes made via the serial link are not retained on power-
down.
The
non-volatile save state
must be reset to the required state each time the instrument is
powered down, replaced with another instrument or the host
computer is powered down.
4 write cycles, the
non-volatile save
is set to 'Enable', any
is set to'Disable', parameter
is not retained on power-down and