Measurement Computing StrainBook/616 - Manual (Page 19)

Using a Sample for Triggering
TTL-level Triggering
StrainBook includes TTL-level triggering through the digital I/O port. A detailed discussion of triggering
begins on page 4-7.
Sync Ports
StrainBook includes two SYNC ports. Up to four StrainBooks can be scan-synchronized and triggered by
connecting one of the two SYNC ports of a unit to a SYNC port on a second StrainBook. StrainBooks can
also be connected in this manner to a SYNC port on a WBK40 or WBK41 module.
Additional information on synchronization begins on page 4-8.
Control, Timing, and Signal Processing
At each sample time, the DSP: (a) reads from the scan sequence table, and (b) accordingly programs a
Control-and-Timing Circuit for the next sample. The Control-and-Timing Circuit waits precisely until the
start of the next sample, then selects:
the input channel
PGA gain
level-shifter offset
A/D input source
The control-and-timing circuit conveys this information to any attached expansion units and precisely
controls the A/D conversion timing.
An EEPROM holds the calibration information needed for real-time sample correction.
The digital I/O port is read and written by the Digital Signal Processor to transfer bytes of digital data.
It may be used as a simple 8-bit input port or as a 32-address byte-wide I/O port.
StrainBooks and the Ethernet, General Information
The most common and highest-performance Ethernet connection for StrainBook is achieved via a
dedicated, point-to-point Ethernet link between the PC and the unit’s Ethernet port. Data transfer rates
in this configuration will accommodate continuous 1 Mreading/sec transfers from the StrainBook to the
PC.
With an enterprise-wide Ethernet network connection, any number of StrainBooks can be connected to the
network. Enterprise-wide Ethernet networks are typically shared amongst a large number of devices. In
such a scenario, the data transfer rates from the StrainBook are dependent on other network traffic at the
time of data transfer.
If you need to have continuous, 1 Mreading/s transfers from the StrainBook, you should
avoid connecting StrainBooks to an enterprise-wide Ethernet network. However, to
improve the data transfer performance of StrainBooks that are connected to such a
network, a factory-installed WBK30 memory option should be employed. Contact the
factory for additional information.
Up to four StrainBooks can be synchronized to each other via their SYNC ports. Each unit has two
identical SYNC ports. Either or both SYNC ports can be used to connect to the units via SYNC cables
CA-74-1 or CA-74-5 (1-foot or 5-foot cables, respectively). The units can be scan-synchronized and
triggered from any other SYNC-connected unit. The StrainBooks are individually connected to the
Ethernet, as indicated in the following figure.
This application is useful when the channel requirements exceed the 64 channel capability of one
StrainBook. It is also useful when the per-channel bandwidth exceeds that which could be accomplished
by a lone StrainBook, or if multiple time bases are required.
StrainBook/616 967794 Operation Reference 2-5