Analog Data Bits - Automation Direct DL405 User Manual

14–12
F4–04DA–2 Analog Voltage Output
Analog
Data Bits
Signal Sign Bit
Bipolar Output
Data
The first twelve bits of the V-memory
location represent the analog data in
binary format.
Bit Value Bit
0 1
1 2
2 4
3 8
4 16 10
5 32 11
The most significant bit (bit 15) is the
sign bit, when the data format for any
channel is selected to be –2047 to
+2047. By controlling this output (Y37 in
our example), you can easily select
positive or negative values.
Programming examples later show how
easy it is to make sign selection part of
your data value.
If an output channel is configured for an
output format of –2047 to +2047, the
maximum data valid value for the lower
12 bits is 2047. This means the 12th bit
(bit 11) must always be "0".
WARNING: If the data value exceeds 2047, the 12th bit becomes a "1", and the
other eleven bits start over at "00000000000". At this point the module's channel
output voltage also goes back to the bottom of its range and begins increasing
again. The RLL program will be expecting a maximum output, but it will be minimum
instead. This can have serious consequences in some applications, and may result
in personal injury or damage to equipment. Therefore, in standard bipolar ranges
(or whenever the output format is –2047 to +2047 in general), be sure that your RLL
program does not create numbers with absolute values greater than 2047.
MSB
Value
1 1
6 64
5 4
7 128
8 256
9 512
1024
2048
MSB
1 1
5 4
MSB
Bit 11 must be "0" for output
format of –2047 to +2047.
V40501
1 1 1 1 9 8 7 6 5 4 3 2 1
3 2 1 0
– data bits
V40501
1 1 1 1 9 8 7 6 5 4 3 2 1
3 2 1 0
– signal sign output
V40501
1 1 9 8 7 6 5 4 3 2 1
1 0
– data bits
LSB
0
LSB
0
LSB
0