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Basic Operation Guide - LEDs, etc.

The three LEDs can give a rough guide as to what possible faults are present. The following indicatins are for a properly functioning unit. Many board and build faults can also casue similar LED indications.

The left GREEN LED is simply the power indicator, but note that it can still glow even when the battery voltage is way below a usable level. It's preferable to measure battery voltage between the FUSE holder (left end) and the nearby GND point of D2. A bench power supply should be capable of 3 amps at 12 Volts, or use a fully charged battery. A steady battery voltage below about 10.5 Volts will not enable the sensor to work properly. A battery charger should never be used as the source of power.

The right ORANGE LED monitors the voltage across the heater. The heater is controlled by the processor and is switched rapidly on and off. There should be a medium brightness rapid flicker detectable during normal operation. When the sensor end is heated (by exhaust gas or a flame) less power is required to maintain the sensor's temperature and the LED dims. If a sensor is not connected at power on then there should be a regular, but faint, pulsed flicker at a couple of flashes per second as the processor tests if the heater is connected.

The centre RED LED is the STATUS and ERROR indicator. During continuous operation this LED should be on solidly (not flashing). A simple on-off-on-off (ie. equal on & off periods) indicates an error condition such as loss of PID lock (heater and Vs/Ip PID) caused by the sensor being too hot or too cold, or in a very rich mixture. The other status indicated is sensor heatup where a long off and a short on flash occurs which should last 15 to 25 seconds from cold, or possibly no time if sensor is already hot.

Testing Using WBo2's In-built Commands

WBo2's serial RS232 port is used to send logged data and for reflashing program memory. WBo2 also has an inbuilt command interpreter that can perform limited internal testing. The eXcel spreadsheet testproc.xls contains commands that can be sent to WBo2, and the expected responses or measurements to be made on the board itself.

To talk to WBo2 first set up Window's Hyperterminal to 19200 baud, and then connect your COM port to WBo2's DB9 to RJ45 adapter. Of course, if you computer doesn't have a COM port, you can use a USB to serial port adapter.

The following table is taken from the testproc spreadsheet. You type the Command into Hyperterminal (unfortunately there is no echo) and you expect to see the indicated Response from WBo2. The Action field indicated what things are occurring, or what to test and check against.




Comment 1    

Comment 2    


> 400F

Stops WBo2's auto-TX mode.




> 0059

place WBo2 into mode 2.

Heater will be turned off also.



> 4000

Narrowband voltage should be 0.00 V.

set PWM 1 output to 0.

0% PWM duty cycle.

Test Point and Connector Voltages

An additional way to test WBo2 is to measure some of the static voltages shown below and to compare them with the indicated values.

Test condition with 6066 sensor J1 - installed, J2 in the 2-3 position, J3 in the 1-2 position. Negative (Black) lead of DVM on GND (left) end of D2. Sensor in free-air. Battery voltage of 12.0 Volts. The voltages (in red) are for when butane is briefly squirted into the end of the sensor and these voltages rapidly change back as the butane dissipates from around the sensor element. The "butane voltages" are just a rough check that the unit is working.

Note that these voltages were obtained from a production unit and the calibration set for a 6066 sensor. 7057/7200 sensor values should be similar. The readings may also depend on the type of voltmeter you use.

	Test Points (grouped as on PCB)
Ip	Tp1 2.74 (1.30)
Vpb	Tp2 3.30 (0.67)
NBsim	Tp6 0.02 (0.90)
SVout	Tp5 4.05 (1.05)

WBLin	Tp3 5.03 (0.01)
WBVout	Tp4 3.53 (0.05)

	Circular connector - Y3
Vs	Y3-1  2.48 (2.48)
Vs/Ip	Y3-2  2.01
Ip	Y3-3  2.75 (1.45)
IpCal	Y3-4  2.91 (1.05)
VGND	Y3-5  2.01 (as for Y3-2)
H-	Y3-6  5.0  (blow into sensor to cool heater - may go down to 1.0 Volt)
H+	Y3-7  12.0 (battery voltage)

	RJ45 I/O Connector - Y1
SVout	Y1-1  4.05 (as for SVout)
Rx	Y1-2  0    (-9.0 Volts if PC connected)
Tx	Y1-3  -9.0
WBlin	Y1-4  5.03 (as for WBlin)
GND	Y1-5  0    (GND)
NBSim	Y1-6  0.02 (as for NBSim)
WBVout	Y1-7  3.53 (as for WBVout)
VBatt	Y1-8  12.0 (as for Battery, ~1.0 or more lower if LD02 is connected)

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