Reference Manual
00809-0100-4697, Rev EA
October 2011
Rosemount 848T
D-8
Application Information
The configuration of the AI function block and its as sociated output channels
depends on the specific application. A typical configuration for the AI block
involves the following parameters:
CHANNEL
The device supports more than one measurement, so verify that the
selected channel cont a ins th e ap propri ate me asureme nt or derived va lue.
Refer to Table 3-5 on page 3-11 for a listing of available channels on the
848T.
L_TYPE
Select Direct when the measurement is in the desired engineering units
for the block output. Select Indirect when converting the measured
variable into another, for example, pressure into level or flow into energy.
SCALING
XD_SCALE provides the range and units of the measurement and
OUT_SCALE provides the range and engineering units of the output.
OUT_SCALE is only used when in indirect or indirect square root.
AI Block
Troubleshooting
Symptom Possible Causes Corrective Action
Mode will not leave OOS Target mode not set. Set target mode to something other than OOS.
Configuration error BLOCK_ERR will show the configuration error bit set. The following are parameters that
must be set before the block is allowed out of OOS:
• CHANNEL must be set to a valid value and cannot be left at initial value of 0.
• XD_SCALE.UNITS_INDEX must match the units in the transducer block
channel value. Setting the units in the AI block automatically sets them in the
XD_BLOCK.
• L_TYPE must be set to Direct, Indirect, or Indirect Square Root and cannot be left at
initial value of 0.
Resource block The actual mode of the Resource block is OOS. See Resource Block Diagnostics for
corrective action.
Schedule Block is not scheduled and therefore cannot execute to go to Target Mode. Typically,
BLOCK_ERR will show “Power-Up” for all blocks that are not scheduled. Schedule the
block to execute.
Process and/or block
alarms will not work. Features FEATURES_SEL does not have Alerts enabled. Enable the Alerts bit.
Notification LIM_NOTIFY is not high enough. Set equal to MAX_NOTIFY. Alarm not linked to host.
Status Options STA TUS_OPTS has Propagate Fault Forward bit set. This should be cleared to cause an
alarm to occur.
Value of output does not
make sense Linearization Type L_TYPE must be set to Direct, Indirect, or Indirect Square Root and cannot be left at
initial value of 0.
Scaling Scaling parameters are set incorrectly:
• XD_SCALE.EU0 and EU100 should match that of the transducer block
channel value.
• OUT_SCALE.EU0 and EU100 are not set properly.
• Both STB on each asic used must by in auto.
Cannot set HI_LIMIT,
HI_HI_LIMIT, LO_LIMIT,
or LO_LO_LIMIT Values
Scaling Limit values are outside the OUT_SCALE.EU0 and OUT_SCALE.EU100 values.
Change OUT_SCALE or set values within range.