Owner's manual

Chapter 4: PowerDAQ Software

Timing and Control

The PowerDAQ DIO clocking and triggering features are extensive and

can be configured in different ways.

Digital Input/Output Clocking

Clocking comprises of two input signals

1. Input clock – used to clock digital input channels in

channel list.

2. Output clock – used to clock digital output channels in

channel list.

You must load the channel list prior to starting the acquisition. Note,

that only –CT and –ST boards support the clocked I/O operations.

Clocking can be controlled by

• Internal Clock (DSP)

• External Clock

• Software clock (non-timed operation only)

External trigger

Digital input and output streamed operation along with ESSI and

counter stream may be triggered by the external event. This event must

be supplied by the customer hardware. IRQC terminal is used as trigger

input. Trigger signal must be a TTL-level signal. Negative, at least 20

nS long, pulse may be used to start and/or stop acquisition. Actual

trigger is detected on the negative (1-0) edge of the incoming trigger

signal. If both start and stop triggers are enabled first pulse will start

acquisition and following will stop it and so on.

Note Maximum trigger line frequency should not exceed

1 kHz to insure proper operation of the DIO board,

but minimum space between two given triggers may

be as short as 1 µS.