EDAM-4200 Series User’s manual Version 1.03
12.2
Module Status
Power-On Reset will let all output go to Power-On Value. The module may accept the host's command to change
the output value. Host Watchdog Timeout will let all digital output go to Safe Value if the host watchdog timeout
flag is set, and the output command will be ignored. The module's LED will go to flash and user must reset the
module status via command to restore normal operation.
12.3
Dual Watchdog Operation
Dual Watchdog = Module Wa Host Watchdog
The Module Watchdog is a hardware reset circuit to monitor the module’s operating status. While working in harsh
or noisy environment, the module may be down by the external signal. The circuit may let the module to work
continues and never halt. The Host Watchdog is a software function to monitor the host’s operating status. Its
purpose is to prevent the network/communication from problem or host halt. While the timeout occurred, the
module will turn the all output into safe state to prevent from unexpected problem of controlled target. The E-4200
module with Dual Watchdog may let the control system more reliable and stable.
12.4
Reset Status
The reset status of a module is set when the module is powered-on or when the module is reset by the module
watchdog. It is cleared after the responding of the first $AA5 command. This can be used to check whether the
module had been reset. When the $AA5 command responds that the reset status is cleared, that means the module
has not been reset since the last $AA5 command was sent. When the $AA5 command responds that the reset status
is set and it is not the first time $AA5 command is sent, it means the module has been reset and the digital output
value had been changed to the power-on value.
12.5
Input counter and Input latch
Input counter:
Each input channel has internal counter used to software count the state change (
falling edge
) of input signal ( max.
300Hz ). The counting value can be read and cleared by sending “
Read digital input counter command
” or “
Clear
digital input counter command
”.
Input latch:
Each input channel has internal latch which is used to latch the pulse signal from the input. This latched state can be
read by sending “
Read latched digital input
“ command and cleared by sending “
Clear latched digital input
”
command. For example, if the digital input is connected to a key switch. The key switch is a pulse signal. The user
may lose the strike information by sending command $AA6. The digital input latch can latch the pulse and ready be
read by sending “
Read latched digital input
“ command. If the latched state=1 means that there is a key strike
occurred.
12.6
Power-on & Safe value
Power-on value:
Power-on value is used to set the module default output value when the module is turned-on or watch dog timeout
reset. This function is especially importance in some application where the specific initial output states are required
User can set power on value by sending
Set power-on/safe value
command
Safe value:
Safe value are used to set the module outputs into the specific values when Host watchdog timeout If The host
watchdog timer is enabled by sending
Set host watchdog timeout value
, the host should send
Host OK
command
periodically within Timeout value to refresh the timer, otherwise the module will be forced to safety state.
Printed Date: 27 February 2018
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