D11.2 | Trim Current |
If the procedure shown above suggests that there is a calibration difference between the MSM400 output and other current monitoring equipment on the loop, it will be necessary to use a calibrated meter to establish which unit is in error. Using the “Set current” routine of the MSM400 can be instructed to provide outputs between 4 and 20mA that the MSM400 considers correct. If these are in error, the “Trim current” routine is used as follows:
The “Trim current” selection sets the current output of the MSM400 either at maximum (supposed to be 20mA) or minimum (supposed to be 4mA) depending on the option selected.
For maximum the display shows:
CURRENT OUTPUT IS
NOW 20mA. MEASURE
CURRENT AND USE ↑ & ↓
TO TRIM THE OUTPUT
Follow the instructions and if the current output is in error, i.e. not 20mA, use the ↑ and ↓ arrows as trimming signals to adjust the value to be exactly 20mA. Each press of the arrow causes an audible signal and adjusts the output value by a discrete step. (approx 6μA)
This process should then be repeated for the 4mA setting. Once the current output is seen to be correct the ON/CLEAR key is used to escape.
Mode Cancelled Warning
If while trimming or fixing the current the analog output returns to its normal mode the message FIXED CURRENT MODE CANCELLED will be displayed. This could occur for three reasons, master has sent the appropriate command, the MSM400 has been powered off then on again, or the output in fixed current mode has been at the same value for 20 minutes.
D.12.0Unknown Instrument
This limited support for unknown control unit is provided so that the identification and basic performance of any control unit can be obtained without having to change to another HHC. This is of particular use in
If the control unit detected is not an MSM400, MSP100 or MLT100 then Unknown instrument is displayed and an access to the parameters is prompted for. If this is selected then the parameters that are present on all transmitters are uploaded, after first setting up any files that are required.
If the instrument conforms to revision 5 or higher of the HART protocol then the manufacturer of the instrument will be available. If it is of an earlier revision then only the model number will be available.
IP258
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