The Honeywell 30731811-001 is the output card for the Basic Controller, Extended Controller, and Multifunction Controller.

This card contains four 4-20 mA analog output circuits to drive analog field devices. The Output card contains four identical circuits plus some decoding logic, interfacing logic, and a power regulator. Each of the identical circuits consists of a hold station chip, a pulse width to analog converter and some buffer transistors. The hold station chip receives an output digital word and the setpoint digital word for the same loop and converts these into pulse-width modulated signals. The setpoint signal is buffered and made available for analog displays where the setpoint meter circuit converts the modulated signal into equivalent analog meter readings. The output signal is converted on the card to a 4-20 mA. by a pulse width to analog circuit and then directed to the terminal panel. The controller can also sends mode parameters and alarm signals to the hold station chips. The alarm signals are buffered and directed to the terminal strip for use by external monitoring equipment.

30731811-001 contains some filtering circuits for control signals (such as SP raise and lower, output raise and lower, Local Manual mode, etc) from analog displays to the hold chips. Potentiometers are provided on the card edge for calibration purposes.

The power to these cards is not switched off by the power switch on the side of the card cage. This allows powering down the box without disturbing the output signals to the field. When the box is powered back up and the processor is started, the output is read from the hold chip back to main memory to provide bumpless startup. The +24 volt line contains a fuse at the rear of the card. An LED on the front of the card gives visual indication of the status of the power to the card.

An LED on the card edge of the output card shows when +24 Vdc is applied to the card.

WPC installs new electrolytic capacitors on all of our output cards.

Troubleshooting Tip: If you have an output card error which does not follow the card when you move the card to the other slot, or which is still there after changing the card, check the box's memory card (Solid State Memory 30750218-010 for the Basic Controller, EDAC Memory 30750786-001 for the Extended Controller, or the 82408667-001 PROM/RAM card for the Multifunction Controller).