Honeywell DR4300 manual Communications, Relay outputs for control and alarms, Failsafe operation

DR4300 Circular Chart Recorder

Communications

The Modbus communication option permits configuration of the unit and monitoring of process variables over a standard multi-drop serial communications link.

Relay outputs for control and alarms

The models with display and keypad are available with output relays, two for each pen channel. These relays can be wired for Normally Open (NO) and Normally Closed (NC) terminals. ON-OFF control can be performed using one relay (relay simplex control) or two relays (relay duplex control).

Any relay not used for control is available for alarming. Two alarm setpoints can be configured for each alarm relay. An adjustable hysteresis of 0.0 % to 100.0 % is configurable for the alarm setpoint.

Analog output for control or retransmission

Depending on the model ordered, a 4 to 20 mA current output may be available for control or retransmission of a process variable (“auxiliary output”).

Failsafe operation

The control function can operate in automatic or manual mode. In automatic the control function works to maintain the process variable at the setpoint entered locally by the operator. During configuration a “failsafe” value can be specified. This value is used as the output at power up and in case of input failure during automatic operation. (When the unit goes to failsafe, the control function goes to manual mode.)

In manual mode the operator enters the output locally. If the recorder has gone to failsafe operation, the operator will be able to change the output value from the failsafe value specified during configuration.

Timer and totalizer options

The recorder is available with timer and totalizer options. The timer can be started locally, remotely, or by an alarm. The unit can be configured to display elapsed time or time remaining. At the end of the timeout period Relay 2 is energized, and remains energized until the timer is reset. The totalizer can be reset locally or remotely; its displayed value can be scaled.

Setpoint Programming Option

The recorder is available with a Setpoint Program option. This feature allows configuration of up to four setpoint programs using a total of twenty-four ramp and soak segments. A setpoint and time is configured for each segment. The program can be set up to include guaranteed soak segments. A plus/minus deviation is configured for all soak segments. Whenever the plus/minus deviation is exceeded, soak timing is frozen.

Display and keypad

In addition to process variables, the display can show output, setpoint, and deviation real time values if the recorder is equipped with optional outputs. The upper display uses four characters to display the input value. The lower display shows other parameters using a two- or three-character label and four- or three- digit values. In addition, status and error messages flash on the lower display when necessary.

2 DR4300 Circular Chart Recorder Product Manual 12/03