Detcon 10B User Manual

Page 9

2.9 O

THER

EATURES

Model 10 control modules include other features which are discussed below.

2.9.1 Flashing Overange

The f lashing overange feature will cause the display to f lash on and off, at approximately one second intervals once the

top of the range has been exceeded. After the signal drops back into the normal range, the display will cease f lashing

and operate normally.

2.9.2 PolySwitch Overcurrent Protection

Model 10 control modules incorporate PolySwitch overcurrent protection components that act as resetable fuses. The

PolySwitch circuit protector is a positive temperature coeff icient resistor that undergoes a large, abrupt change in resis-

tance when an overcurrent or high temperature heats it above a specif ic point. Normally just tens of milliohms, the

resistance of the PolySwitch protector increases orders of magnitude when switched. This increase limits current to several milliamps.

When the current or temperature fault that caused the device to switch has been substantially reduced, the PolySwitch

device resets, allowing normal circuit operation to resume. The protector requires no manual resetting or replacement.

Four separate Poly Switches monitor and protect the following circuitry: the 4-20 mA signal input loop, the 4-20 mA

output signal loop, the 24 VDC input power loop, and the 24 VDC output power loop to the sensor.

2.9.3 Initialization Mode

If the calibration switch on the side of the PCB is pressed during insertion of the PCB or during the f irst 2 seconds

after power up, the unit will enter an initialization mode. The initialization acts as a master reset and should only be

executed to restore the controller and its internal memory to factory default values. Initializing the controller will over-

write all factory calibration values, alarm set points, 485 ID, and range settings. Initialization is performed at the factory

prior to shipment and is not normally required in the f ield.

If the initialization is activated, the display will show It. The following operations are performed by the controller dur-

ing an Initialization.

1. Default zero (250) and span (4000) values are written to nvram.

2. The controller reads the status of the 3d/2d switch.

3. If 3d is selected the default range is set to 999. If 2d is selected the default range is set to 99.

Model 10 Single Channel Digital Control Module PG.9

MSB

LSB

Fault alarm status

Fault alarm latching/non-latching mode

Alarm 1 alarm status

Alarm 1 latching/non-latching mode

Alarm 1 ascending/descending mode

Alarm 2 alarm status

Alarm 2 latching/non-latching mode

Alarm 2 ascending/descending mode

Not used

Test mode status