TELEDYNE API T703U - Relay PCA Watchdog Indicator (D1); Table 9-1: Relay Board Status Leds

Principles of Operation Teledyne API T703/T703U Calibrator Operation Manual
188
Table 9-1: Relay Board Status LEDs
LED
COLOR
DESCRIPTION
FUNCTION/INDICATION
D1
Red
Watchdog Circuit; I
2
C bus
operation.
Blinks when I
2
C bus is operating properly
D2
Yellow
Zero Air Pump (option) Status
When lit the zero air AC pump is running.
D3-6
SPARE
D7
Green
Photometer Meas/Ref Valve
Status
When lit the valve open to the Measure
gas path; when not lit while instrument is
running, the valve is open to the
Reference gas path.
D8
Green
Zero Air Shutoff Valve (option) Status
When lit, ZA shutoff valve open.
D9
Green
O
3
Pump Status
When lit, O
3
pump running
D10
Green
T703U Divert Valve Status
when lit, divert valve open.
D11
Green
T703U O
3
Generator Valve Status
When lit, O
3
generator valve open.
D12 - 14
SPARE
D15
Green
Photometer Lamp Heater Status
When lit the photometer UV lamp heater
is on
D16
Green
O
3
Generator Lamp Heater
When lit the O
3
generator UV lamp heater
is on
Relay PCA Watchdog Indicator (D1) 9.2.3.4.
The most important of the status LEDs on the relay board is the red I
2
C Bus
watchdog LED. It is controlled directly by the calibrator‟s CPU over the I
2
C bus.
Special circuitry on the relay PCA watches the status of D1. Should this LED
ever stay ON or OFF for 30 seconds (indicating that the CPU or I
2
C bus has
stopped functioning) this Watchdog Circuit automatically shuts all valves and
turns off all heaters and lamps.
07223D DCN7107