Analog Data Bits - Automation Direct DL405 User Manual

Output Enable Output bit 15 is the Output Enable
Bit control bit for all eight channels. When
the bit is off, all eight channel output
currents decrease to their lowest level,
which is 4 mA for connected loads.
Disabling the outputs also clears all eight
output data registers. To resume analog
output levels, first the Output Enable
control bit must turn on. Then, the CPU
must write new data to each channel to
restore the output current for that
channel.

Analog Data Bits

The first twelve bits of the data word
represent the analog data in binary
format.
Bit
0
1
2
3
4
5
Module Since the module has 12-bit resolution,
Resolution the analog signal is made of 4096 counts
ranging from 0–4095 (2
20 mA scale, sending a 0 produces a 4
mA signal, and 4095 gives a 20 mA
signal. This is equivalent to a binary
value of 0000 0000 0000 to 1111 1111
1111, or 000 to FFF hexadecimal. The
graph to the right shows the linear
relationship between the data value and
output signal level.
Each count can also be expressed in
terms of the signal level by using the
equation shown. The following table
shows the smallest signal change that
occurs
increased by 1 LSB.
4 to 20mA
Value Bit
1 6
2 7
4 8
8 9
16 10
32 11
12
when the digital value is
Signal Range
F4–08DA–1 8-Ch. Analog Current Output
MSB
1 1 1
5 4 3
MSB
1 1 1
Value
5 4 3
64
128
256
512
1024
2048
20mA
). For the 4 to
4mA
Resolution + H * L
H = high limit of the signal range
L = low limit of the signal range
Span Divide By
(H – L)
16mA 4095
V40501
LSB
1 1 1 9 8 7 6 5 4 3 2 1
2 1 0
– Output Enable Bit
OFF = Disable (and clear)
ON = Enable
V40501
LSB
1 1 1 9 8 7 6 5 4 3 2 1
2 1 0
– data bits
0 4095
4095
Smallest Change
3.91 mA
15–9
0
0