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Technical Specifications
Xtium2-CXP PX8 User's Manual
Note 3.4: Interfacing directly to a TTL (also called Push-Pull) Output
FG/system GND
GND
Frame Grabber System
Interfacing TTL Output via a Line Buffer/Driver
TTL signal source & Buffer Driver
(example: 74ACT244)
RS-422 / TTL (+) input
Figure 40: Interfacing TTL to TTL Shaft Encoder Inputs
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NOTE: User must select the Shaft Encoder TTL level when using this mode
CORACQ_PRM_SHAFT_ENCODER_LEVEL = CORACQ_VAL_LEVEL_TTL (0x1)
).
Note 3.5: Interfacing to a TTL using a Bias Voltage
RS-422 (-) input
FG/system GND
DC
Bias Voltage
+2V
GND
Frame Grabber System
Interfacing TTL Output to RS-422 Inputs
via a Line Buffer/Driver
TTL signal source & Buffer Driver
(example: 74ACT244)
100 ohm
RS-422 / TTL (+) input
Figure 41: Interfacing TTL to RS-422 Shaft Encoder Inputs using a Bias Voltage
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If necessary, a TTL input can be connected to the RS-422 / TTL input using a bias voltage
(however it is recommended to use the Shaft Encoder TTL mode described in Note 3.4. The
graphic shows a single-ended driver signal interfaced to the RS-422 input.
•
RS-422 (-) input is biased to a DC voltage of +2 volts. This guarantees that the TTL signal
connected to the RS-422 / TTL (+) input will be detected as a logic high or low relative to
the (-) input.
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The TTL shaft encoder ground, the bias voltage ground, and the Xtium2-CXP PX8 computer
system ground must be connected together.
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DC voltage for the RS-422 (-) input can be generated by a resister voltage divider.
•
Use a single battery cell if this is more suitable to your system.
•
NOTE: User must select the Shaft Encoder RS-422 level when using this mode
CORACQ_PRM_SHAFT_ENCODER_LEVEL = CORACQ_VAL_LEVEL_422 (0x2)
).
