| 摘要 |
<p>A loop-powered intelligent transmitter for process control variables is provided which can operate at an average current in excess of the minimum value of current that can flow in the loop (A, B). In order to keep the average current drawn down to the actual loop current, execution of a control program by a microprocessor (2) incorporated in the transmitter is slowed down to the extent necessary to reduce current demand of the transmitter to that available. Slowing down is preferably accomplished by means (24) for sensing when a current deficit occurs and placing the microprocessor in sleep mode to reduce current consumption until the deficit is made up. Entry into sleep mode may be deferred during time critical operations of the microprocessor.</p> |
