Siemens SITRANS LUT400 Series - Ma Control; Ma Output; Verifying the Ma Range

Page 72 SITRANS LUT400 (HART) – OPERATING INSTRUCTIONS A5E33329501
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General Operation
mA Control
mA output
The SITRANS LUT400 has one mA output, used for communications with other devices.
Example:
Configuring the mA output to send a 4 to 20 mA signal corresponding to a scaled value of
10% to 90% of maximum process level on a 60 m transducer:
Verifying the mA range
Checks that the external device can track the entire 4 to 20 mA range sent by the SITRANS
LUT400. Follow the steps below if actual mA readings differ between the LUT400 (shown in
2.5.8. Current Output Value ) and an external device (such as a PLC).
1. To test the loop current, set
2.5.1. Current Output Function to Manual, then set the
value to use in
2.5.7. Manual Value .
2. Check that the external device displays the same mA reading as the mA value set
above.
3. If external device reading differs from the set manual value on the LUT400, adjust
the reading on the external device to match the reading on the LUT400.
Parameter
Sample
Value
Description
2.5.1. Current Output
Function
or 2.5.2. Cur-
rent Output Function
LEVEL send mA proportional to level reading
2.5.3. 4 mA Setpoint 6 set 4 mA at process level equal to 10% of maximum
(Low Cal minus High Cal)
a
a.
If the level reading drops below 6 m, the mA output drops below 4 mA.
2.5.4. 20 mA Setpoint 54 set 20 mA at process level equal to 90% of maxi-
mum (Low Cal minus High Cal)
b
b.
If the level reading rises above 54 m, the mA output rises above 20 mA.
2.5.5. Minimum mA
Limit
3.5 set minimum mA level below 4 mA
2.5.6. Maximum mA
Limit
22.8 set maximum mA level above 20 mA
Note: If default values (4 and 20 mA) are used for the minimum and maximum mA
limits, the mA output (shown in 2.5.8. Current Output Value ) will remain at the set
mA limit, even if the level reading falls below/rises above the mA setpoints.