Peak And Valley Hold Reset; Flag Bits; Peak/Valley Reset Truth Table; Mapping Bit Position To Channel Number - Siemens SIMATIC 505 Installation And Operation Manual

Peak and Valley
Hold Reset

Flag Bits

SIMATIC 505–2556 Installation and Operation Guide
Outputs Y28 and Y29 are used to reset the valley or peak hold functions.
The operation during reset is dependent on whether the hold function is
enabled for each individual channel.
Figure 3-15 shows how the peak value and the valley value react during
reset.
Peak or Valley Hold Function
Enabled
Disabled
Figure 3-15 Peak/Valley Reset Truth Table
When not using peak or valley hold, WX49 – WX54 return flag bits for each
of the functions, and each of the channels may be interrogated with ladder
logic instructions.
The flag bits correspond to the 16 channels in the module. The LSB or bit 16
corresponds to channel 1, and the MSB or bit 1 corresponds to channel 16.
See Figure 3-16.
MSB
Bit # 1 2 3
Channel # 16 15 14 13
Figure 3-16 Mapping Bit Position to Channel Number
Alarm flags (WX49) The alarm flag bit is the logical OR of the low alarm
bit (WX5) and the high alarm bit (WX50) for each channel. This allows one
simple check to determine if an alarm exists on a channel. These alarm bits
reset automatically when the alarm condition is no longer true. In the event
that an alarm exists on a channel, the ladder logic may determine whether
the alarm has reached the low alarm or the high alarm.
Reset to current input value
Reset to zero
4 5 6 7 8 9
12 11 10 9 8
Advanced Function Programming
10 11 12 13 14 15
7 6 5 4 3 2
LSB
16
1
3-23