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Reference Manual
00809-0400-4728, Rev AA
June 2011
3-21
Rosemount 644
Analog Input (AI)
Function Block
Status
Along with the measured or calculated PV value, every F
OUNDATION fieldbus
block passes an additional parameter called STATUS. The PV and STATUS
are passed from the Transducer Block to the Analog Input Block. The
STATUS can be one of the following: GOOD, BAD, or UNCERTAIN. When
there are no problems detected by the self-diagnostics of the block, the
STATUS will be GOOD. If a problem occurs with the hardware in the device or
the quality of the process variable is compromised for some reason, the
STATUS will become either BAD or UNCERTAIN depending upon the nature
of the problem. It is important that the Control Strategy that makes use of the
Analog Input Block is configured to monitor the STATUS and take action
where appropriate when the STATUS is no longer GOOD.
Simulation
Simulate replaces the channel value coming from the Sensor Transducer
Block. For testing purposes, it is possible to manually drive the output of the
Analog Input Block to a desired value. There are two ways to do this.
Manual Mode
To change only the OUT_VALUE and not the OUT_STATUS of the AI
Block, place the TARGET MODE of the block to MANUAL. Then, change
the OUT_VALUE to the desired value.
Simulate
1. If the SIMULATE switch is in the OFF position, move it to the ON
position. If the SIMULATE jumper is already in the ON position, you
must move it to off and place it back in the ON position.
NOTE
As a safety measure, the switch must be reset every time power is
interrupted to the device in order to enable SIMULATE. This prevents a
device that is tested on the bench from getting installed in the process with
SIMULATE still active.
2. To change both the OUT_VALUE and OUT_STATUS of the AI Block,
set the TARGET MODE to AUTO.
3. Set SIMULATE_ENABLE_DISABLE to ‘Active.’
4. Enter the desired SIMULATE_VALUE to change the OUT_VALUE
and SIMULATE_STATUS_QUALITY to change the OUT_STATUS.
If errors occur when performing the above steps, be sure that the
SIMULATE jumper has been reset after powering up the device.