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1.8 Digital O/P
The module's output have 3 different situation :
<1>
Safe Value
. If the host watchdog timeout status is set,
the output is set to Safe Value. While the module receive the output
command like @AA(Date) or #AABBDD, the module will ignore
the command and return "!". And will not change the output to the
output command value.
The host watchdog timeout status is set
and store into EEPROM while the host watchdog timeout
interval expired and only can be cleared by command ~AA1
. If
user want to change the output it need to clear the host watchdog
timeout status firstly and send output command to change the output
into desired value.
<2>
PowerOn Value
. Only the module reset and the host
watchdog timeout status is clear, the module's output is set to
predefined Power On Value.
<3>
Output Command Value
. If the host watchdog timeout
status is clear and user issue a digital output command like @AA
(Data) or #AABBDD to module for changing the output value. The
module will response success (receive>).
1.9 Latch Digital I/P
For example, use connect the key switch to Digital input channel of
a digital input/output module and want to read the key stoke. The
Key input is a pulse digital input and user will lost the strike. While
reading by command $AA6 in A and B position, the response is that
no key stroke and it will lose the key stroke information. Respectely,
the read latch low digital input command $AAL0 will solve this
problem. When issue $AAL0 command in A and B position, the
response denote that there is a low pulse between A and B position
for a key stroke.
