ICP DAS USA I-7521, Руководство пользователя

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I-7521/I-7522/I-7522A/I-7523/I-7524/I-7527 User’s Manual,Ver2.5 Aug.2015
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Chapter 4 DI/DO and WatchDog
4.1
DO Operation Principles

The DO of the I-752N module will revert to its initial start values
when powering on for the first time.
 If the “$AAZNV” command is received, the DO output will change
to desired state. All DO will then remain in the same states until
the next “$AAZNV” command is received.

If the I-752N module is reset by the hardware watchdog, all DO
will immediately revert to their power-on values. However, these
power-on values may be different from the original states that
existed prior to the reset, so the DO states stored on the Host PC
may be different from real DO states that were latched in the
I-
752N module. An “$AAZNV” command must be sent from the
Host PC in order to reset these DO to their expected states.
 The “$AA5” command can be used to detect a hardware
watchdog reset. Refer to Sec.4.5 for more information. If the
I-
752N module is reset by the hardware watchdog, an “$AAZNV”
command must be sent from the Host PC to reset the DO to their
expected states.

If the host watchdog fails, all DO values will revert to their safe
values immediately and the module status will be set to 04. If an
“$AAZNV” is sent by the Host PC, the modules will ignore the
command and return “!” as a warning. The“~AA1” command can
be used to clear the module status to 00, then the I-752N module
will again be able to accept an “$AAZNV” command.
4.2
DI Operation Principles
The I-752N series DI commands are as follows:
(1)
#** synchronized sampling. All modules will sample
the DI at the same time
(2)
$AA4 reads the synchronized sampling data.
(3)
$AAYN reads the current state of the DI