EXAMPLE 2 DATA IMPOSITION
For a second example, take the case of the MASTER issuing a message, this time to
change an Alarm Setpoint value again directed at device 2.
The MASTER sends the following sequence.
The receipt of the message by device number 2 is exactly as in the previous example.
This time, however, the ! indicates the message is a data imposition and applies to the
Alarm Setpoint (AS). There are two alarms, the index 001 indicates that it applies the
first Alarm ( Alarm 2 would have an index of 002). Device 2 updates the Alarm
setpoint with 80.0 and then responds with an acknowledgement as shown below.
There is one important point to understand here. The new Alarm Setpoint has been
programmed into the device and will be used to control the Alarm operation.
However, it has not been programmed into non-volatile memory within the instrument,
so when power is removed, it will be lost and on powering the instrument again, the
original setpoint value will be restored.
The next example shows how programmed data is stored to non volatile memory.
EXAMPLE 3 ACTION
APPENDIX E
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