Operation Without Process Alarm; Special Features Of The 432 Digital Input Module - Siemens S5-155U System Manual

Technical Description
8.1.3
Special Features of the
432 Digital Input Module
Modes
Reaction time
Operation without process
alarm
Settings on the module
8 - 10
The 432 digital input module accepts 32 process signals and emits a
process alarm if the logic state at one of its inputs changes.
You can operate the module in the following modes:
• • without process alarm ("normal" digital input module)
• • with initiation of a process alarm via interrupt
• • with initiation of a process alarm via IB 0 (only in conjunction
with CPU 948)
To operate the module with process alarm via IB 0, you must address
it in the normal (P) area from byte 128 because
• • the automatic updating of the process image might acknowledge a
process alarm without the system program having detected and
interpreted this alarm;
• • only modules addressed in the normal (P) area can initiate a
process alarm via IB 0.
The time for reaction of the module to a process alarm is mainly
determined by the input circuitry. You can set the reaction time to one
of the values 0.3 ms, 1 ms or 3 ms with switch S5. Note that the
filtering effect decreases with shorter reaction times, and interference
may be received as useful signals (effect of the line length, see the
technical specifications).
To operate the module without process alarm, you can insert it at any
slot for I/O modules and address it in the entire I/O area. If you
address it in the area PB/PY 0 to PB/PY 124, it will be within the
automatic updating of the process image.
Make the following settings on the module to operate it without
process alarm:
Step Action
1 Open jumpers X3 and X4
2 Set switch rows S1 and S2 to Off
0
1
2
3
4
5
: OFF 6
: ON 7
Figure 8-3 Switch Settings for Operation without Process Alarm
The setting for switch row S3 is arbitrary in this mode.
S1
S2
0
IR-A
1
IR-B
IR-C 2
IR-D 3
4
IR-E
IR-F 5
6
IR-G
INT 7
System Manual
C79000-B8576-C199-03
Bit 0
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7