In the selective sampling mode, a measured value is encoded on the
central initiative of the CPU. At the start of conversion, the module
must be addressed once with a write operation (T PW) by the user
program. An active bit (T = 1) is set during encoding.
With the transition to T = 0, the measured value becomes valid. With
non-constant cycle times, there may be non-periodic measured value
aquisition. If you operate the module in this mode, you must set a
module address from 128 to 255. You can also use the address range
from 0 to 127 for selective sampling after appropriate programming in
DB 1 of the user program.
Time-controlled program
processing
Another method is that of time-controlled program processing. With
this method, certain program segments (e.g. FB 13) are automatically
inserted into program processing at the 100 ms rate by a time-
controlled block (OB 13). A constant timebase is thus achieved.
FB 13
SPRM-B
LEN=22
ABS
SHEET 1
SEGMENT 1
NAME: SELSAMPL
EXAMPLE OF SELECTIVE SAMPLING
0005
:
0006
:
0007
:L
PW 128
READ ANALOG VALUE
0008
:T
FW 128
IN TO AUX: FLAG FW 128
0009
:A
F 129.2
SCAN ACTIVITY =1?
000A
:JC
= END
IF = 1, JUMP TO END
000B
:T
FW 10
IF = 0, MEASURED VALUE IN FW 10
000C
:T
PB 128
INITIATE SAMPLING
000D
END :
(1ST VALUE INVALID AFTER START)
000E
:
000F
:
0010
:BE
Function block
You can read analog values of analog input modules with a function
block from the "basic functions" package.
BASP (output inhibit)
The BASP signal is not interpreted by the 465 analog input module.
The 465 Analog Input Module
System Manual
9 - 58
C79000-B8576-C109-03
