ADLINK Technology NuDAQ ACL-8454, Руководство пользователя

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Installation
Figure 2.14 Gate source of counter #1 ~#4
The jumper setting is flexible for users‘ applicati ons. There are two
configurations: jumper installed or NOT installed. The default state
of jumper is not installed and the counter can be controlled externally
or just pull-high enable. When the jumper installed, the gate is
cascaded from counter #6 outp ut and the
ExtG n signal is an output
signal.
Note that the external gate source must NOT be used when
cascaded gate source is used. The Table 2.5 shows the reference
number of the gate control jumpers and its corresponding
counter/timer channels number. The default setting of every jumper
is also shown.
Jumper
Label Gate source of
counter/timer Default gate
source
G1 GATE1 ExtG1
G2 GATE2 ExtG2
G3 GATE3 ExtG3
G4 GATE4 ExtG4
Table 2.5 Reference number of clock setting jumpers
2.11 Counter Outputs
The timer/counter output signals ( COUT n ) of 8254 are controlled by
clock source, gate control and software programming. All the output
of the 8 independent counters are sent to the 37 pins connector
directly. The
COUT6 and COUT12 of the two pairs of cascaded
counters are also send to connector. Therefore, totally 10 counter
outputs are sent to connector, see 'Pin assignment' for
corresponding signal pin number.
In addition, the output signal may be used as clock source or gate
control of the cascaded counters, see the above sections. It is
possible to cascaded two counters by jumpers. The counters output
COUT6 , COUT12 are also used as internal interrupt source (refers
to 'Interrupt System').