Global Specialties PB-507 - Manual - Manual (Page 19)

19
Figure 12
Description
•
Eight bicolor LEDs (b7…b0) are used to indicate logic high (red) or low
(green) for eight digital inputs.
•
The TTL or CMOS input switching levels can be selected by pressing
button TTL/CMOS. The High and Low thresholds for CMOS depend on
the positive voltage set in the DC Power supplies module.
•
The LEDs will light red when the inputs are 2.0V or higher when TTL is
selected, or 70% of the +V voltage or higher when CMOS is selected.
•
The LEDs will light green when inputs are 0.8V or less when TTL is
selected, or 30% of the +V voltage or less when CMOS is selected.
•
In the case of an unconnected input or an input not at valid logic level the
corresponding LED will turn off.
•
If CMOS input is selected and +V voltage is less then 1V, the Logic
indicators module will not work. In this case the CMOS LED will flash.
6.9 Logic probe
Front-panel controls
Figure 13 shows the Logic probe controls on the front panel of the trainer.
Figure 13
Description
•
The Logic probe is a logic troubleshooting instrument that detects Logic
High (red LED), Logic Low (green LED) and single shot events (yellow
LED).
•
Two operation modes are provided: Memory or Pulse. The operation
mode can be set by pressing the MEM/PULSE button.
•
PULSE mode is the normal operation mode for pulse and level detection.