ICP DAS USA tET Series User Manual page 13

Ethernet I/O Modules

Built-in Multi-Function I/O
The DO modules support these functions:
 Power-on Value: On boot up, the DO value will be set to the Power-on value.
 Safe Value:
If Modbus TCP communication is lost for a specific period, the DO value will be set to the
user-defined safe value.
 A PWM (Pulse-Width Modulation) Function:
Each of DO channel can be set to a different frequency (50 or 100 Hz Max.) and duty cycle,
also work either independently or simultaneously. The term "High Duty Cycle" describes the
duration of 'ON' time in proportion to the regular interval or 'period' of time. Similarly, the
term "Low Duty Cycle" corresponds to the duration of the 'OFF' time. Consequently, it is not
necessary to keep switching from ON to OFF from remote a controller. In this way, the module
reduces the complexity required for the control system and enhances timing accuracy.
Note: Because of the characteristics of the relay functions, it is recommended that the PWM
on modules with relay functions is not used for extended periods.
The DI modules support these functions:
 Can be Used as a 32-bit High Speed Counter
 High/Low Latched Status Commands:
The modules provide commands to read the status of any
digital input channels that are latched high or latched low.
The following is an example that shows the usefulness of the
latched digital input. If we wish to read a key stroke from a
key switch connected to the digital input channel of a module,
the input signal of the key stroke is a pulse signal as shown in the figure.
If we just use the read digital input status command to read the signal and we cannot send the
command during the B period due to some reasons, then we will lose the key stroke
information. However, with the read latched digital input command, we can still get the key
stroke information even we are not able to send command in B period.
 Frequency Measurement:
This function can be used to retrieve the digital input counter value at specific times and
calculates the frequency (Hz, Max. 3.5 kHz). Rather than polling via a remote host, the module
can determine the frequency directly, reducing the communication delay caused by two ends
and also improves the accuracy of the frequency measurement. In order to applying for
more applications, this module provides 3 scan modes and 4 moving average methods for user
to select the best way in their applications.
ICP DAS CO., LTD. tET/tPET IO Series User Manual, Ver. 2.4, Sep. 2023, P13