HBM Genesis GEN5i User Manual page 554

554
The result is shown in the read only "Scale result": 240 mDegrees/Clock
pulse
E Clock shift: (TDC position)
This setting can be used to shift the position of the 0 degrees indication on
screen automatically. If for example the TDC signal is not exactly the 0
degrees position but comes in at 36.1 degree, set the "Clock shift" to 36.1.
Note Once the TDC point has been establish all samples recorded prior to TDC
detection will be scaled backward from this point.
F TDC enable
When this setting is enabled, GEN DAQ systems will use the External
Trigger input signal to automatically establish the 0 Degree reference
(TDC: Top Dead Center) for rotational measurements.
G TDC delay
The TDC delay parameter can be used to skip some of the beginning TDC
signals, eg. to avoid jitter TDC problems while starting engines.
Example: If this setting is set to 5 then the 0 degree position is linked to the
th
5 occurrence of the TDC signal after start of recording in the GEN DAQ
system.
H Use qualifier
This setting can be used to separate the ignition cycle from the exhaust
cycle. Typically the ignition and exhaust cycle together are treated as a 720
degree rotation cycle. For every 360 degree rotation a TDC pulse will be
generated by the engine. For the GEN DAQ system to separate the 0
degree TDC pulse from the pulse appearing at 360 degrees we need a
second signal: TDC qualifier.
The TDC qualifier is implemented by using the alarm function of the GEN
DAQ analog channels driving the alarm output of the GEN DAQ mainframe.
The alarm status will be AND-ed with the external trigger input to produce
the proper TDC signal selection. No additional wiring is required other then
measuring the qualification signal by one of the analog channels.
Separate the ignition from exhaust cycle, we could measure the cylinder
pressure on e.g. Channel 1. Set the Alarm level of Channel 1 to be active
above 10 PSI. Disable all other alarm settings for all other channels in the
system. Enable the use Qualifier setting. If channel 1 measures less than
10 PSI, the alarm output signal will disable the TDC detection. As soon as
the pressure exceeds 10 PSI the detection of the TDC is enabled. If no
TDC is detected before the pressure drops below 10 PSI again, the TDC
detection is disabled again.
GEN5i
I2679-4.0 en