Michell Instruments WM281, Руководство пользователя

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WM281/291 User’s Manual
6 97463 Issue 1, July 2014
INstallatIoN
2.5.4 Digital Serial Interface
The WM281/291 Transmitters are equipped with an RS485 communication port which
provides users with the following features:
• RS485 Modbus output for use as a control signal within a single or
multidrop system
• All transmitter variables and diagnostics can be accessed and modified
using the Digicor2 Communications Kit, available from Michell.
• With use of suitable calibration equipment and trained personnel, unit re-
calibration can be performed
2.5.4.1 Modbus Register Holding Map
Please refer to Appendix B.
2.6 Analog Output Configuration
On the WM281/291 Transmitters, configuration of the three analog outputs can be
achieved automatically via the RS485 Modbus interface with the Digicor2 Configuration
Software (see Section 4) or on the WM291 manually via the LCD display keypad.
Output Channel 1
• The output signal is equal to the range -30 to +70°C (-22 to +158°F)
(unless another output scale is ordered)
Output Channel 2
• The output signal is equal to the range 0 to 100% RH
Output Channel 3
• Dew point range -99.9 to +212 (includes both °F and °C)
• Frost point range -99.9 to +212 (includes both °F and °C)
• Mixing ratio range (g/kg) 0 to 500 g/kg
• Absolute humidity range (g/m
3
) 0 to 600 g/m
3
• Enthalpy range -40 to +1500 kJ/kg
These are the electronic minimum/maximum limits which the transmitter is capable of
calculating.