Siemens SIMATIC TIWAY 1 User Manual page 34

2.8.2.1 The External Input Point
The input point latches a high level. The option parameter of the REPORT
EXTERNAL INPUT STATUS command determines when to reset and latch the
external input. The values for the command option are:
Options 00 and 01 report whether the "on" condition ever occurred, but not
report the current state of the external input point. Option 02, however, reports
the instantaneous value of the input and should be used for time dependent
applications. The response will be either 00 indicating that the input is off, or 01
indicating that the input is on. The complete specifications for the input point
are given in the UNILINK Adapter Installation and Operation Manual
(TIWAY–8106).
2.8.2.2 The External Output Point
The MODIFY EXTERNAL OUTPUT STATUS command either turns the
external output point ON or turns it OFF. The corresponding voltage levels are
given in the UNILINK Adapter Installation and Operation Manual
(TIWAY–8106). The command code FC, along with either 00 or 01 will
respectively turn off or turn on the output point. The adapter will return the
command code in response. The initial state of the External Output Point is zero
after a reset or power-up. A remote "Adapter Good" lamp can be set up using this
point by connecting it to a remote control center panel lamp so that when the
host computer applications software issues the MODIFY EXTERNAL
OUTPUT STATUS command to turn on the output point, the lamp will light. If a
problem occurs that causes the adapter to reset, the lamp will be extinguished.
UNILINK HOST ADAPTER
USER MANUAL
OPERATION AND APPLICATION
00 = Read the input, do not reset the latch.
01 = Read the input, then reset the latch.
02 = Reset the latch, then read the input.
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