Measurement Computing USB-1616HS-BNC User Manual page 29

USB-1616HS-BNC User's Guide
Connecting the USB-1616HS-BNC to an encoder
You can use up to two encoders with each USB-1616HS-BNC in your acquisition system. Each A and B signal
can be made as a single-ended connection with respect to common ground.
Differential applications are not supported.
For single-ended applications:
 Connect signals A, B, and Z to the counter inputs on the USB-1616HS-BNC.
 Connect each encoder ground to GND.
 +5 V to power encoders is available from the DB37 connector.
You can also connect external pull-up resistors to the USB-1616HS-BNC counter inputs by placing a pull-up
resistor between any input channel and the encoder power supply. Choose a pull-up resistor value based on the
encoder's output drive capability and the input impedance of the USB-1616HS-BNC. Lower values of pull-up
resistors cause less distortion, but also cause the encoder's output driver to pull down with more current.
Wiring to one encoder
CTR0 (pin 9)
CTR1 (pin 27) To Encoder ―B‖
CTR2 (pin 8)
Figure 18. Connections from single encoder to DSUB37 pins on the USB-1616HS-BNC
The "A" signal must be connected to an even-numbered channel and the associated "B" signal must be
connected to the next higher odd-numbered channel. For example, if "A" were connected to counter 0, then "B"
would be connected to counter 1.
Connect each signal (A, B, Z) as a single-ended connection with respect to the common ground. The encoder
needs power from an external power output (typically +5 VDC). Connect the encoder's power input to the
power source and connect the return to the digital common of that source.
Wiring for two encoders:
Differential connections are not applicable.
Each signal (A, B) can be connected as a single-ended connection with respect to the common digital ground
(GND). Both encoders need power from an external power source (typically +5 VDC).
Connect each encoder's power input to the external power source. Connect the return to digital common (GND)
on the same source.
: Figure 18 shows the connections for one encoder to a USB-1616HS-BNC module.
+5VDC (pin 23)*
To Encoder ―A‖
To Encoder ―Z‖
* Other DGND pins—pins 14, 25, 28, or 33—can also be used.
The following figure illustrates single-ended connections for two encoders.
DGND (pin 5)
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Functional Details