Measurement Computing StrainBook/616 - Manual (Page 23)

The following apply:
One of three clocks can be used to drive the StrainBook’s acquisition scan rate. These are:
- the internal clock
- an external clock connected via pin 20 of the front panel DB25 connector labeled
“Digital I/O, Ext. Clock, TTL Trigger”
- the global sync (G-SYNC) input from the SYNC ports on the StrainBook’s rear panel
Both the SYNC connector input and the external clock input can be divided down.
When a StrainBook is in Master Mode both the trigger condition and the scan timing are output
on the SYNC port. The global trigger (G-TRIG) is selected instead of the TTLTRIG input from
the front panel DB25 labeled “Digital I/O, External Clock, TTL Trigger.”
Whether the StrainBook is using its internal scan clock or external clock input [from the front panel
DB25] it can be programmed to output the clock on the SYNC connector. In either case, the StrainBook is
behaving as a synchronization master. Other StrainBooks connected to the master via a SYNC port
should be programmed as synchronization slaves.
When a StrainBook is programmed as a synchronization slave it will derive its scan
period from the SYNC port.
If the slave StrainBook must be triggered at the same time as the master StrainBook
the slave unit should use TTL Trigger as its trigger source.
Not all trigger modes are supported for multiple StrainBook systems.
SYNC Notes :
When a StrainBook is programmed as a synchronization slave the TTL trigger source is
automatically derived from the SYNC port.
When a StrainBook is programmed as a synchronization master it will output its trigger
condition on the SYNC port.
When synchronizing two or more StrainBooks the slave StrainBooks should have at least
0.1 µs of dead time in the scan period. By “dead time,” we mean a duration in which no
channels are sampled. This accommodates for fundamental differences in StrainBook
clocks.
All StrainBooks that are connected via SYNC cables can be scan-synchronized to
within 0.1µs of each other.
Not all trigger modes are supported for multiple StrainBook systems.
A maximum of 4 units can be synchronized, scan-synchronous (post trigger).
SYNC cables are not to exceed a total combined length of 15 feet (4.57 m).
StrainBook/616 967794 Operation Reference 2-9