Measurement Computing USB-1602HS-2AO - Manual (Page 28)

USB-1602HS-2AO User's Guide Functional Details
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Figure 20. Encoder connections to the SCSI connector*
* Connections can alternately be made to the associated screw-terminals of a connected TB-102 terminal
connector.
You can get the relative position and velocity from the encoder. However, during an acquisition, you cannot get
data that is relative to the Z-position until the encoder locates the Z-reference.
Debounce feature
Each input can be debounced from 500 ns to 25.5 ms (total of 16 selections) to eliminate extraneous noise, or to
switch induced transients. Encoder input signals must be within 0 and 5.5 volts and the switching threshold is
typically 1.5 volts. If the encoder stops rotating, but continues to generate signals (due to it being mounted to a
vibrating or noisy machine), you can use the debounce feature to eliminate false edges. Choose an appropriate
debounce time and apply it to each encoder channel. Refer to the "Debounce function" section on page 23 for
additional information regarding debounce times.
Scan period values
The USB-1602HS-2AO clears all counter channels at the beginning of the acquisition, so the values returned
during scan period 1 are always zero. The values returned during scan period 2 reflect what happened during
scan period 1. In general, the output of each channel’s counter is latched at the beginning of each scan period
(called the start-of-scan.) Every time the USB-1602HS-2AO receives a start-of-scan signal, the counter values
are latched and are available to the USB-1602HS-2AO.
The scan period defines the timing resolution for the USB-1602HS-2AO. If you need a higher timing resolution,
shorten the scan period.
Timer/pulse generators
The USB-1602HS-2AO has two timer/pulse generator signals ( TMR/PWM0 and TMR/PWM1 ) with
programmable duty cycle. Each timer is capable of generating a programmable pulse width wave with a
programmable frequency in the range of 0.01123 Hz to 24 MHz. The pulse and period range is 20.83 ns to
89 seconds.
Ground (to DGND pin)
Encoder
CTR4 A to Encoder “A”
CTR4 B to Encoder “B”
CTR4 Z to Encoder “Z”
+5V PWR