Connecting Counter/Timer I/O Signals; Synchronizing Conversions On Multiple Boards - Keithley DAS-8 Series User Manual

Make sure that all digital signals are TTL-level compatible. Use the
digital common as the return for all digital signals.
Caution:
To prevent damage to DAS-8 Series boards, do not apply
voltages exceeding TTL maximum levels (
input pins.

Connecting Counter/Timer I/O Signals

Refer to 82C54 documentation for information on connecting counter/
timer I/O signals to the clock input pin, gate input pin, and output pin of
any available counter/timers on a DAS-8 Series board. Table 2-2 lists
several companies that provide documentation for the 82C54.

Synchronizing Conversions on Multiple Boards

You can use a hardware external clock source to synchronize conversions
on multiple DAS-8 Series boards. In addition, you can use the output of
the OUT1 pin (pin 5) on a DAS-8/PGA(G2) or DAS-8/AO board (acting
as a timing master) to synchronize conversions on additional DAS-8
Series boards.
Figure 4-13 illustrates how you can synchronize conversions on multiple
boards, using both an external clock source and a DAS-8/PGA/G2 board.
Note that in both cases, boards 1, 2, and 3 must be configured to use an
external clock.
Figure 4-14 illustrates the use of C/T0 on the 82C54 on board 1 to divide
the rate of the master clock by the programmed count. This allows you to
synchronize conversions on board 1 to a rate different from that of the
master board. Note that when you use C/T0 to divide the rate of the
master clock, C/T0 must be configured for counter/timer mode 2 (rate
generator mode). Refer to Section 2, 82C54 Counter/Timer Circuitry, or
to your 82C54 documentation for more information.
4-14
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