DL205 Analog Manual, 7th Edition Rev. D
6-17
Chapter 6: F2-04RTD 4-Channel RTD Input
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D
Reading Magnitude Plus Sign Values (Multiplexing)
The DL230 CPU does not have the special V-memory locations that allows for automatic
enabling the data transfer. Since all channels are multiplexed into a single data word, the
control program must be set up to determine which channel is being read. Since the module
appears as X input points to the CPU, it is very easy to use the active channel status bits to
determine which channel is being monitored.
NOTE:
DL230 CPUs with firmware release version 1.6 or later required for multiplexing ladder.
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This instruction masks the sign bit. Without this,
the values used will not be correct so do not forget
to include it.
Loads the complete data word into the
accumulator. The V-memory location depends on
the I/O configuration. See Appendix A for the
memory map.
LD
V40401
ANDD
K7FFF
SP1
X40
X41
X50
Store Channel 1
OUT
V2000
When X40, X41, and X50 are off, channel 1 data is
stored in V2000. C0 is reset to indicate that
channel 1’s value is positive.
SET
C0
X37
RST
C0
If X37 is on, the data value represents a negative
temperature. C0 is set to indicate that channel 1’s
value is negative.
X40
X41
X51
Store Channel 2
OUT
V2001
When X40 is on and X41 and X51 are off, channel
2 data is stored in V2001. C1 is reset to indicate
that channel 2’s value is positive.
SET
C1
X37
RST
C1
If X37 is on, the data value represents a negative
temperature. C1 is set to indicate that channel 2’s
value is negative.
X40
X41
X52
OUT
V2002
SET
C2
X37
RST
C2
X40
X41
X53
OUT
V2003
SET
C3
X37
RST
C3
When X40 and X52 are off and X41 is on, channel
3 data is stored in V2002. C2 is reset to indicate
that channel 3’s value is positive.
If X37 is on, then the data value represents a
negative temperature. C2 is set to indicate that
channel 3’s value is negative.
When both X40 and X41 are on and X53 is off,
channel 4 data is stored in V2003. C3 is reset to
indicate that channel 4’s value is positive.
If X37 is on, the data value represents a negative
temperature. C3 is set to indicate that channel 4’s
value is negative.
Store Channel 3
Store Channel 4
Содержание DL205
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