Black Box IEEE 1284 Betriebsanweisung PDF herunterladen (Seite 47)

The Black Box Toolkit Page 47 of 98

• How many events we wish to generate in a sequence – remember we need to

include the off periods as events too

• The decimal port value for a given event. We can determine this by clicking on the

LEDs and making a note of the decimal port value

• The duration of each “on” and “off” period in milliseconds

In this case assume that we are simulating a scanner that generates pulses every

1993ms. So pulses that are a millisecond wide might be generated at 1993, 3986, 5979,

7972, 9965ms and so on. So we would need to create an “on” event which lasts for 1ms

and occurs every 1993ms. To do this we would need to enter the following values into the

generator.

Here we are using line 5 (powered digital output) to simulate the scanner TTL pulse. This

line has a decimal port value of 128. Note: you must enter an even number of events you

wish to generate (250 in the example). Once you have filled out the table click on “Apply”

then “OK”. When you click on “Apply” the completed sequence will appear.

Here we can see that a 1ms pulse occurs every 1993ms. Finally we specify a Real Time

Log file and run the sequence. When we run the sequence we should ensure that our

remote PC is ready to accept our TTL pulses. Typically a remote PC would accept pulses

using it parallel port or dedicated interface board. You should also be aware that creating

long sequences will take up at least 60Mb of hard drive space per minute of runtime and

that the resulting RTL files will be slower to analyse.

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Black Box IEEE 1284 Betriebsanweisung Seite 47