ICP DAS USA PET-7060, User Manual

Page: 146 / 156

Appendix D: Modbus Application Notes
PET-7000 DIO User Manual, May 2009, V1.00, EMH-013-10----------
146
Digital Input High/Low Latch
DI Latch
Function
Enable Latch
Clear ALL
Latch (High)
Clear ALL
Latch (Low)
Latch Status
(High)
Latch Status
(Low)
Address 00150 00032 00033 10032~1XXXX 10064~1XXXX
XXXX: Depends on the type of ET-7000 series module
For example: The user connects a key switch to the digital input channel of a digital input
module and wants to read the keystrokes. The key input is a pulse digital input signal, and the
user will miss the stroke. When reading the DI status for DI address 10000 by Modbus
command 02 in A and B position, the response will be that
no keystroke has been made and the keystroke information will be lost. In contrast, reading
the latched low digital input at DI address 10064 using Modbus command 02 will solve this
problem. When issuing 02 command in A and B position, the response denotes that there has
been a low pulse between the A and B position indicating a keystroke.
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