HART PSK achieves practicality
Dual-speed HART and multiple soft modems now on one, low-power microchip
Back in 2001, HART Specification version 6 defined Phase Shift Keying (PSK), an alternative to Frequency Shift Keying (FSK) that multiplied HART data communication rate from 1,200 bits per second (bps) to 9,600 bps. At the time, few end users or vendors noticed because, in general, HART applications ran fine at 1,200 bps. Why add more electronics, expense, and above all, energy consumption, considering the 4-20 mA loop limits available current to about 3.5 mA?
But time marches on. Instrument engineers added HART-accessible, smart self-diagnostics, additional sensor signals and calculated outputs such as mass flow, valve signatures and alarms. Configuration options increased, and control systems added remote configuration, calibration and…
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