Digital I/O Control Terminal (Dio Ctl) For Pull-Up/Down Configuration; Ground Terminals (Agnd, Dgnd); Synchronous Dac Load Terminal (Syncld); Counter Terminal (Ctr) - Measurement Computing USB-3100 Series User Manual

USB-3105 User's Guide
For more information on digital signal connections
For more information on digital signal connections and digital I/O techniques, refer to the Guide to
Signal Connections (available on our web site at www.mccdaq.com/pdfs/DAQ-Signal-Connections.pdf).

Digital I/O control terminal (DIO CTL) for pull-up/down configuration

All digital pins are floating by default. When inputs are floating, the state of unwired inputs are undefined (they
may read high or low). You can configure the inputs to read a high or low value when they aren't wired. Use the
connection (pin 54) to configure the digital pins for pull-up (inputs read high when unwired) or pull-
DIO CTL
down (inputs read low when unwired).

To pull up the digital pins to +5V, wire the

To pull down the digital pins to ground (0 volts), wire the
(pin 50, 53, or 55).

Ground terminals (AGND, DGND)

Eight analog ground (
Three digital ground (
connections.

Synchronous DAC load terminal (SYNCLD)

The synchronous DAC load connection (pin 49) is a bidirectional I/O signal that allows you to simultaneously
update the DAC outputs on multiple devices. You can use this pin for two purposes:

Configure as an input (slave mode) to receive the D/A LOAD signal from an external source.
When the SYNCLD pin receives the trigger signal, the analog outputs are updated simultaneously.
SYNCLD pin must be logic low in slave mode for immediate update of DAC outputs
When the SYNCLD pin is in slave mode, the analog outputs can be updated immediately or when a positive
edge is seen on the SYNCLD pin (this is under software control.)
The SYNCLD pin must be at a low logic level for DAC outputs to update immediately. If the external source
supplying the D/A LOAD signal is pulling the SYNCLD pin high, no update will occur.
Refer to the "USB-3100 Series" section in the Universal Library User's Guide for information on how to update
DAC outputs immediately.

Configure as an output (master mode) to send the internal D/A LOAD signal to the SYNCLD pin.
You can use the SYNCLD pin to synchronize with a second USB-3105 and simultaneously update the DAC
outputs on each device. Refer to
Use InstaCal to configure the SYNCLD mode as master or slave. On power up and reset the SYNCLD pin is set
to slave mode (input).
Refer to the "USB-3100 Series" section in the Universal Library User's Guide for information on how to
configure the USB-3105 with the Universal Library.

Counter terminal (CTR)

The CTR connection (pin 52) is the input to the 32-bit event counter. The internal counter increments when the
TTL levels transition from low to high. The counter can count frequencies of up to 1 MHz.
AGND ) connections provide a common ground for all analog voltage output channels.
) connections provide a common ground for the
DGND
Synchronizing multiple units
terminal pin to the
DIO CTL
terminal pin to a
DIO CTL
on page 17.
15
Functional Details
terminal pin (pin 56).
+5V
terminal pin
DGND
, , and
DIO CTR SYNCLD +5V