Flowserve MX HART Field Unit - Manual (Page 19)

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MX/QX HART Field Unit FCD LMENIM2340-00 – 1/14
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3
Software
3.1 HART Protocol
The system uses the HART protocol to communicate over the HART network with other HART devices. The HART
protocol is a master/slave communication service for process control devices. HART digital signaling is an extension of
conventional analog signaling allowing the network signal to ride on the 4-20 mADC analog process signal. It uses
1200 bps binary phase-continuous Frequency-Shift-Keying (FSK), where a high frequency current is superimposed on
a low-frequency (typically 4-20 mADC) analog current.
3.2 HART Parameters
Table 3.1 – HART Parameters
Parameter Value
HART Version 7.3
Expanded Device Type = Manufactuer ID + Device Type 0x3008
Physical Layer Supported FSK
Physical Device Catagory Actuator
Maximum Number of Burst Messages 3
Maximum Number of Event Messages 1
Size of the Event Queue 6
Maximum Number of Trends 2
Size of the Trend Buffer 12
Default Number of Preambles 1 5
3.2.1 Analog Input Ratings
Table 3.2 – Analog Input Ratings
Maximum current 2 30.0 mA
Maximum voltage 50 V
Current over-range
(Primary Variable Out of Limits) Analog Input > 21 mA
Analog Input < 3 mA
(HART communication may fail, if Analog Input <2 mA.)
Multi-drop current draw Approximately 2 mA
1. Field Device must have minimum 5 preambles, and maximum 20 preambles.
2. The analog input is automatically bypassed, if the maximum loop current is reached. The field device will continue to check the circuit for overload on a periodic basis,
and will restore the connection if the overload clears.