Analog Output - ICP DAS USA I-7021 User Manual

A.5 Analog Output
Besides setting by the analog output commands, the
analog outputs can be set by two other conditions.
When the host watchdog is enabled and a host watchdog
timeout occurs, the "safe value" is loaded into the analog
output ports. The analog output commands have no effect
on the analog output ports until the host watchdog timeout
status is cleared. The host watchdog timeout status is
saved in the EEPROM. The status is not changed even
after power-on reset. It can be cleared only by the reset
host watchdog timeout status command ~AA1. See
Section A.2 for host watchdog details.
When the module is powered on and the host watchdog
timeout status is cleared, the "power-on value" is loaded
into the analog output ports. If the host watchdog timeout
status is not cleared on power-on, then the safe value is
loaded into the analog output ports.
The safe value is set by the ~AA5 command for the I-7021
and I-7021P, and by the ~AA5N command for the I-7022,
M-7022, I-7024, I-7024R, M-7024, M-7024L, M-7024R,
M-7024U and M-7028. The power-on value is set by the
$AA4 command for the I-7021 and I-7021P, and by the
$AA4N command for the I-7022, M-7022, I-7024,
I-7024R, M-7024, M-7024L, M-7024R, M-7024U and
M-7028.
When the module receives the analog output command
#AA(data) or #AAN(data), if the host watchdog timeout
status is not cleared, then it responds '!' to indicate that the
command is ignored. If the host watchdog timeout status
182 I-7021/22/24, M-7022/24/28 User Manual, Rev: B2.3