Measurement Computing StrainBook/616 - Manual (Page 21)

Digital I/O Connections
Digital I/O can be connected for 16-bit mode or 8-bit mode via the StrainBook’s DB25F high-speed digital
I/O connector labeled “Digital I/O, Ext. Clock, TTL Trigger.” The following signals are accommodated by
the connector.
High-Speed Digital I/O Lines
TTL Trigger Input (TTLTRG) (pin 13)
+15 V (pin 23), -15 V (pin 22), 50 mA max. (each)
two +5 V (pin 19 and pin 21), 250 mA max. (total)
External Clock Input (pin 20)
Digital Clock (pin 18), only used for WBK17 applications
two Digital Grounds (pins 24 and 25)
Reference Note:
The 16-bit and 8-bit modes are both detailed in Chapter 8. That chapter includes a separate
pinout for each mode.
Triggers
External signals can be used to start or synchronize the data acquisition process.
StrainBook supports the following trigger sources:
Software Trigger.
This trigger event is generated by a software command from the PC
without waiting for an external event. This feature may be used to begin a data acquisition
immediately or to force an acquisition to occur if the expected trigger did not occur.
Digital Trigger.
Digital (or TTL-level) triggering (either rising- or falling-edge input) is
performed by digital logic connected to the digital expansion connector.
Multi-Channel Trigger.
Here, the trigger event is a combination of measured channel
values. StrainBook's Digital Signal Processor (DSP) performs multi-channel triggering. The
DSP samples the specified channels; if programmable conditions are met, a trigger is
generated. Multi-channel triggering examines digitized data, and the trigger latencies are
much greater.
Digital-Pattern Trigger:
This expanded digital-trigger capability allows data collection to
start when a user-defined 16-bit digital pattern is matched on the digital I/O connector.
This feature is useful when trying to capture noise, vibrations or some other physical
disturbance; such as those that can occur in a programmed logic controller’s digitally
sequenced process.
Reference Note:
Trigger Information is detailed in Chapter 7.
StrainBook/616 967794 Operation Reference 2-7