
4-16
Cabling and Wiring
●
XPCLK — is the external pacer clock input, described in the next
section and in “Clock Sources” on page 2-10. Use the digital-input
terminal DI0/XPCLK for connecting this signal.
●
DOSTB — is the digital output strobe, described in “Using Digital
Control Signal DOSTB” on page 2-18. Use the DOSTB terminal for
connecting this signal.
Connecting and Synchronizing Multiple Boards
You can synchronize up to three DAS-1800 Series boards using trigger
and gate signals from the main I/O connectors. Each board can run at the
same or a different conversion rate as the other boards in the system.
The onboard pacer clock is designed to be tightly coupled with trigger
and gate operations. After each board receives the trigger or gate,
conversions begin within a defined period of time. If each board is
programmed for a different conversion rate, the first conversion on each
board occurs after this time period and subsequent conversions occur at
the programmed rate.
Figure 4-14 shows two connection schemes for synchronizing multiple
boards. Both schemes are using the onboard pacer clock to time
acquisitions.
Figure 4-14. Two Connection Schemes for Synchronizing Multiple Boards
Trigger or
Gate
(optional)
TGIN
TGIN
TGOUT
TGIN
TGIN
TGIN
TGIN
Trigger or
Gate
Board 0
Rate a
Board 0
Rate a
Board 1
Rate b
Board 1
Rate b
Board 2
Rate c
Board 2
Rate c
a. Scheme 1
b. Scheme 2
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