The A881 is a microprocessor based auto manual controller which is designed to control and display control parameters. The instrument serves the purpose of an A/M Controller along with an indicator with retransmission output. As an A/M controller, the instrument accepts 4-20 mA input from possible sources like DCS and gives at the output in the normal AUTO mode. During the possible breakdown, the control shifts from the AUTO mode to the MANUAL mode, and the user can now control the output 4-20 mA from the control keys provided on the front panel. This transfer is bumpless. Even in case of failure of A/M station, the controller continuos its control in auto mode. The optional auto bias feature of the instrument allows even manual to auto transfer bumpless. The bias is set automatically in manual mode to allow this bumpless transfer and then it can be changed by the same push buttons in auto mode. External feedback signal o/p from the A/M station allows controller to track A/M output in manual mode. The rates of change of output (in manual mode) and bias (in auto mode) are 1% and 10% per sec.. The instrument has a 4 digit display which displays the Output parameters as configured by the user. The instrument also accepts another 4-20 mA input, displays as a 4 digi
