Martel Electronics MC1200 - Manual (Page 23)

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Figure 17. Connection Using Current Loop
5.2-1 HART™ Resistor Selection
The MC1200 can be set-up so that the 250 ohm resistor required for Hart™ configuration
devices resides inside the MC1200. Enabling the MC1200's internal 250 ohm resistor
eliminates the need to manually add a series resistor during a Hart™ calibration process.
NOTE: When the MC1200's internal 250 resistor is enabled, maximum load driving capability
drops from 1000 ohms @ 20mA to 750 ohms @20mA.
Enable/Disable Procedure
1. Remove the battery cover and remove the 2 screws that are at the top of the case.
2. Remove the 2 screws on the bottom or lower portion of the case.
3. Gently remove the top half of the case from the bottom.
4. Figure 10a. shows the location of the Hart™ jumpers.
5.3 Measuring Pressure
Note: The Martel Pressure Module connector 700mA needs to be purchased to connect
pressure module to calibrator.
Note: The MC1200 is compatible with BETA Calibrator Pressure Modules. The accessory
BPPA-100 is required for pressure measurement.
Note: Pressure is not read from modules with frequency or pulse train mode enabled.