2. SYSTEM CONFIGURATION
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(6) To eliminate incorrect input at the remote I/O modules, design the A2C
system considering the following.
(a) Measures on turning ON and OFF the power
1) When turning ON the power, turn ON the remote I/O modules
first, and then, turn ON the A2C. Or, turn ON the A2C and the
remote I/O modules together at the same time.
2) When turning OFF the power, turn OFF the A2C first, and then,
turn OFF the remote I/O modules. Or, turn them OFF together at
the same time.
Power supply for the remote I/O modules indicates the following.
(1) I/O module power supply: Power supplied to the I/O module power supply Is converted to
5 VDC inside the system and used in the internal circuit of the I/O module.
(2) Input external power supply: Power supply for input modules
(3) Output external power supply: Power supply for output modules
See the following manual for details.
A2CI/0 Module User's Manual
(b) Measures against momentary power failure for the I/O module
Momentary power failure of the power supply of the I/O module may
cause incorrect input.
1) Cause for incorrect input due to momentary power failure
The I/O module hardware converts the I/O module power supply
(24 VDC) to 5 VDC inside the module.
If momentary power failure occurs in the I/O module, incorrect
input occurs if I/O refresh is executed within duration (A) shown
below because: (Time from occurrence of external power supply
OFF to turning OFF of internal 5VDC) > (ON to OFF response
time of input module).
External supply 24 VDC
(for I/O module power supply
and input external power supply)
When the input external power supply is turned
input (Xn)turnsoff afterthe ON-OFF responsetime
ofthe input module.