2 1 D3–04AD 4-Channel

2 1 D3–04AD 4-Channel
D3–04AD
4-Channel
Analog Input
In This Chapter. . . .
Ċ Module Specifications
Ċ Setting the Module Jumpers
Ċ Connecting the Field Wiring
Ċ Module Operation
Ċ Writing the Control Program
12
2–2
D3–04AD 4-Channel Analog Input
Module Specifications
D3–04AD
4-Channel Analog Input
The following table provides the specifications for the D3–04AD Analog Input
Module. Review these specifications to make sure the module meets your
application requirements.
Analog Input
Configuration
Requirements
Number of Channels
4
Input Ranges
1 – 5V, 4 – 20 mA
Resolution
8 bit (1 in 256)
Channel Isolation
Non-isolated (one common)
Input Type
Differential or Single ended
Input Impedance
1 MW minimum, voltage
250W current
Absolute Maximum Ratings
0 – +10V maximum, voltage
0 – 30 mA maximum, current
Linearity
"0.8% maximum
Accuracy vs. Temperature
"70 ppm / _C maximum
Maximim Inaccuracy
1% maximum at 25_ C
Conversion Method
Sequential comparison
Conversion Time
2 ms maximum
Power Budget Requirement
55 mA @ 9V
External Power Supply
24 VDC, "10%, 65 mA, class 2
Operating Temperature
32° to 140° F (0° to 60_ C)
Storage Temperature
–4° to 158° F (–20° to 70_ C)
Relative Humidity
5 to 95% (non-condensing)
Environmental air
No corrosive gases permitted
Vibration
MIL STD 810C 514.2
Shock
MIL STD 810C 516.2
Noise Immunity
NEMA ICS3–304
Noise Rejection Ratio
Normal mode: –6 dB/250Hz
Common mode: 60dB/60Hz (–5 to 10V)
The D3–04AD Analog Input appears as a 16-point module. The module can be
installed in any slot configured for 16 points. See the DL305 User Manual for details
on using 16 point modules in DL305 systems. The limitation on the number of analog
modules are:
S For local and expansion systems, the available power budget and
16-point module usage are the limiting factors.
2–3
D3–04AD 4-Channel Analog Input
Setting the Module Jumpers
Connecting the Field Wiring
Wiring Guidelines
Your company may have guidelines for wiring and cable installation. If so, you should
check those before you begin the installation. Here are some general things to
consider.
S Use the shortest wiring route whenever possible.
S Use shielded wiring and ground the shield at the signal source. Do not
ground the shield at both the module and the source.
S Don’t run the signal wiring next to large motors, high current switches, or
transformers. This may cause noise problems.
S Route the wiring through an approved cable housing to minimize the risk
of accidental damage. Check local and national codes to choose the
correct method for your application.
User Power Supply The D3–04AD requires a separate power supply. The DL305 bases have built-in 24
VDC power supplies that provide up to 100 mA of current. If you only have one
Requirements
analog module, you can use this power source instead of a separate supply. If you
have more than two analog modules, or you would rather use a separate supply,
choose one that meets the following requirements: 24 VDC "10%, Class 2, 65mA
current (or greater, depending on the number of modules being used.)
D3–04AD
4-Channel Analog Input
There are four jumpers located on the
module that select between 1–5V and
4–20 mA signals. The module is shipped
from the factory for use with 1–5V
signals.
If you want to use 4 – 20 mA signals, you
have to install a jumper. No jumper is
required for 1 – 5V operation. Each
channel range may be selected
independently of the others.
Range
Jumper
1 – 5V
Removed
4 – 20 mA
Installed
2–4
D3–04AD 4-Channel Analog Input
Custom Input
Ranges
Occasionally you may have the need to connect a transmitter with an unusual signal
range. By changing the wiring slightly and adding an external resistor to convert the
current to voltage, you can easily adapt this module to meet the specifications for a
transmitter that does not adhere to one of the standard input ranges. The following
diagram shows how this works.
Internal
Module
Circuitry
Field wiring
D3–04AD
4-Channel Analog Input
+
-
+ch1
50mA
Current
transmitter
(single ended)
+
Jumper
Removed
R
-ch1
250W
-
0V
R=
Vmax
Imax
R = value of external resistor
Vmax = high limit of selected voltage range
Imax = maximum current supplied by the transmitter
Example: current transmitter capable of 50mA, 1 - 5V range selected.
R=
5V
R = 100 ohms
50mA
NOTE: Your choice of resistor can affect the accuracy of the module. A resistor that
has "0.1% tolerance and a "50ppm / _C temperature coefficient is recommended.
2–5
D3–04AD 4-Channel Analog Input
Current Loop
Transmitter
Impedance
Standard 4 to 20 mA transmitters and transducers can operate from a wide variety of
power supplies. Not all transmitters are alike and the manufacturers often specify a
minimum loop or load resistance that must be used with the transmitter.
The D3–04AD provides 250 ohm resistance for each channel. If your transmitter
requires a load resistance below 250 ohms, then you do not have to make any
adjustments. However, if your transmitter requires a load resistance higher than 250
ohms, then you need to add a resistor in series with the module.
Consider the following example for a transmitter being operated from a 36 VDC
supply with a recommended load resistance of 750 ohms. Since the module has a
250 ohm resistor, you need to add an additional resistor.
R 500
R – Resistor to add
Tr – Transmitter Requirement
Mr – Module resistance (internal 250 ohms)
DC Supply
0V
+36V
R
+
–
Two-wire Transmitter
Module Channel 1
–
250W
+
D3–04AD
4-Channel Analog Input
R = Tr – Mr
R = 750 – 250
2–6
D3–04AD 4-Channel Analog Input
Removable
Connector
The D3–04AD module has a removable connector to make wiring easier. Simply
squeeze the tabs on the top and bottom and gently pull the connector from the
module.
Wiring Diagram
Note 1: Terminate all shields of the cable at their respective
signal source.
Internal
Module
Wiring
D3–04AD
4-Channel Analog Input
Note 2: Unused channels should be shorted to 0V or have the
Jumper installed for current input for best noise immunity.
Note 3: When a differential input is not used 0V should be
connected to the – of that channel.
+
See Note 1
+
CH3 Differential
Current Transmitter
+
–
+
OV
–
3
1
–
CH1 Differential
Voltage Transmitter
CH2 SingleĆended
Voltage Transmitter
+
–
+
OV
2
+
–
–
CH4
Not
Used
See Note 2
+
CH1
250
CH2
250
CH3
0
V
0
V
Internally
Connected
-
-
D3–04AD
CH 1
2
3
4
CH
DSPY
SEL
+
–4
+24
V
Analog
Switch
+
250
+
0V
– +
24VDC
ANALOG INPUT
A–D
Convertor
CH4
+24VDC
0V
0V
0V
250
-
Internal
Circuitry
+
1
–
+
2
–
0
V
0
V
+
3
–
+
4
–
0
V
24
V
1
2
3
4
1
2
4
8
16 DSPY
32
64
128
2–7
D3–04AD 4-Channel Analog Input
Module Operation
Channel Scanning
Sequence
Before you begin writing the control program, it is important to take a few minutes to
understand how the module processes and represents the analog signals.
The D3–04AD module supplies 1 channel of data per each CPU scan. Since there
are four channels, it can take up to four scans to get data for all channels. Once all
channels have been scanned, the process starts over with channel 1.
You do not have to select all of the channels. Unused channels are not processed, so
if you select only two channels, then each channel will be updated every other scan.
I/O Update
Channel 1
Scan N
Execute Application Program
Channel 2
Scan N+1
Channel 3
Scan N+2
Channel 4
Scan N+3
Channel 1
Scan N+4
Read the data
Store data
Even though the channel updates to the CPU are synchronous with the CPU scan,
the module asynchronously monitors the analog transmitter signal and converts the
signal to a 8-bit binary representation. This enables the module to continuously
provide accurate measurements without slowing down the discrete control logic in
the RLL program.
D3–04AD
4-Channel Analog Input
Scan
2–8
D3–04AD 4-Channel Analog Input
Understanding the You may recall the D3–04AD module appears to the CPU as a 16-point module.
Some of the points are inputs to the CPU and some are outputs to the module. These
I/O Assignments
16 points provide:
S an indication of which channel is active.
S the digital representation of the analog signal.
D3–04AD
4-Channel Analog Input
Since all I/O points are automatically mapped into Register (R) memory, it is very
easy to determine the location of the data word that will be assigned to the module.
D3–04AD
8pt
Relay
8pt
Output
8pt
Output
050
–
057
040
–
047
030
–
037
16pt
Input
020
027
–
120
127
4ch.
(Analog)
010
017
–
110
117
16pt
Input
000
007
–
100
107
R 002, R012
R 000, R010
R 011
MSB
1
1
7
R 001
LSB
MSB
1
1
0
LSB
0
1
0
0
1
7
- not used
Within these two register locations, the individual bits represent specific information
about the analog signal.
All Channel
Scan Output
The most significant point (MSP)
assigned to the module acts as an output
to the module and controls the channel
scanning sequence. This allows
flexibility in your control program.
If this output is on, all channels will be
scanned sequentially. If the output is off,
you can use other points to select a
single channel for scanning.
Scan
Out 117 Channel Input
N
Off
None
N+1
On
1
N+2
On
2
N+3
On
3
N+4
On
4
N+5
On
1
N+6
Off
None
N+7
Off
None
R011
MSB
LSB
1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1
7 6 5 4 3 2 1 0
- scan all channels
2–9
D3–04AD 4-Channel Analog Input
Single Channel
Scan Outputs
The first four points of the upper register
are used as inputs to tell the CPU which
channel
is
being
processed.
(Remember, the previous bits only tell
the module which channels to scan.) In
our example, when input 110 is on the
module is telling the CPU it is processing
channel 1. Here’s how the inputs are
assigned.
Input
Active Channel
110
1
111
2
112
3
113
4
R011
MSB
LSB
1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1
7 6 5 4 3 2 1 0
- scan a single channel
R011
MSB
LSB
1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1
7 6 5 4 3 2 1 0
- channel selection inputs
D3–04AD
4-Channel Analog Input
Active Channel
Selection Inputs
The upper register also contains two
additional outputs that can be used to
choose a single channel for scanning.
These outputs are ignored if the channel
scan output is turned on.
(Note, our example shows outputs 114
and 115. Your output point will depend on
where you have installed the module.)
Out 114 Out 115 Channel
Off
Off
1
On
Off
2
Off
On
3
On
On
4
2–10
D3–04AD 4-Channel Analog Input
D3–04AD
4-Channel Analog Input
Analog Data Bits
The first register contains 8 bits which
represent the analog data in binary
format.
Bit
Value
Bit
Value
0
1
4
16
1
2
5
32
2
4
6
64
3
8
7
128
R001
MSB
LSB
0
1
7
0
1
0
- analog data bits
Since the module has 8-bit resolution, the analog signal is converted into 256
“pieces” ranging from 0 – 255 (28). For example, with a 1 to 5V scale, a 1V signal
would be 0, and a 5V signal would be 255. This is equivalent to a a binary value of
0000 0000 to 1111 1111, or 00 to FF hexadecimal. The following diagram shows how
this relates to each signal range.
1V – 5V
4 – 20mA
+5V
20mA
1V
4mA
0
255
0
255
Each “piece” can also be expressed in
terms of the signal level by using the
equation shown. The following table
shows the smallest signal levels that
could possibly result in a change in the
data value for each signal range.
Range
1 to 5V
4 to 20mA
Resolution = (H–L)/255
H = high limit of the signal range
L = low limit of the signal range
Highest Signal
Lowest Signal
Smallest Change
5V
1V
15.6 mV
20mA
4mA
62.7 µA
Now that you understand how the module and CPU work together to gather and
store the information, you’re ready to write the control program.
2–11
D3–04AD 4-Channel Analog Input
Writing the Control Program (DL330 / DL340)
Identifying the
Data Locations
Since all channels are multiplexed into a single data word, the control program must
be setup to determine which channel is being read. Since the module provides input
points to the CPU, it is very easy to use the channel status bits to determine which
channel is being monitored.
D3–04AD
8pt
Output
8pt
Output
050
–
057
040
–
047
030
–
037
16pt
Input
4ch.
(Analog)
020
027
–
120
127
010
017
–
110
117
16pt
Input
000
007
–
100
107
R 002, R012
R 000, R010
R 011
MSB
Single Channel on
Every Scan
R 001
LSB
1
1
7
D3–04AD
4-Channel Analog Input
8pt
Relay
1
1
0
MSB
- not used
0
1
7
LSB
0
1
0
The following example shows a program that is designed to read a single channel of
analog data into a Register location on every scan. Once the data is in a Register,
you can perform math on the data, compare the data against preset values, etc. This
example is designed to read channel 1. If you choose another channel, you would
have to add a rung (or rungs) that use the channel select bits to select the channel for
scanning. You would also have to change the rung that stores the data.
Read the data
374
Store channel 1
110
DSTR1
R001
F51
BCD
F86
DOUT
R400
F60
This rung loads the data into the accumulator on
every scan. (You can use any permissive contact.)
The DL305 CPUs perform math operations in
BCD. This instruction converts the binary data to
BCD. (You can omit this step if your application
does not require the conversion.)
The channel selection inputs are used to let the
CPU know which channel has been loaded into the
accumulator. Channel 1 input has been used in the
example, but you could easily use a different input
for a different channel. By using these inputs to
control a DOUT instruction, you can easily move
the data to a storage register. The BCD value will
be stored in R400 and R401. (Two bytes are
required for four digit BCD numbers.)
2–12
D3–04AD 4-Channel Analog Input
Reading Multiple
Channels over
Alternating Scans
The following example shows a program that is designed to read multiple channels
of analog data into Register locations. This example reads one channel per scan.
Once the data is in a Register, you can perform math on the data, compare the data
against preset values, etc.
Scan all channels
374
117
D3–04AD
4-Channel Analog Input
OUT
Read the data
117
Store channel 1
110
Store channel 2
111
Store channel 3
112
Store channel 4
113
DSTR1
R001
F51
BCD
F86
DOUT
R400
F60
DOUT
R402
F60
DOUT
R404
F60
DOUT
R406
F60
Turn on output 117, which instructs the module to
scan all channels.
This rung loads the data into the accumulator. This
rung executes for all channels.
The DL305 performs math operations in BCD. This
instruction converts the binary data to BCD. (You
can omit this step if your application does not
require the data in BCD format.)
The channel selection inputs are used to let the
CPU know which channel has been loaded into the
accumulator. By using these inputs to control a
DOUT instruction, you can easily move the data to
a storage register. Notice that the DOUT
instruction stores the data in two bytes. (Two bytes
are required for four digit BCD numbers.)
2–13
D3–04AD 4-Channel Analog Input
Single or Multiple
Channels
The following example shows how you can use the same program to read either all
channels or a single channel of analog data into Register locations. Once the data is
in a Register, you can perform math on the data, compare the data against preset
values, etc.
Select all channels
000
001
117
OUT
000
114
OUT
Single Channel
001
003
000
115
Input 001 selects single channel scan. Inputs 002
and 003 select which channel by turning on
outputs 114 and 115 as necessary.
114
115
Channel
Off
On
Off
On
Off
Off
On
On
Ch. 1
Ch. 2
Ch. 3
Ch. 4
OUT
Read the data
000
001
Store channel 1
110
Store channel 2
111
Store channel 3
112
Store channel 4
113
DSTR1
R001
F51
BCD
F86
DOUT
R400
F60
DOUT
R402
F60
DOUT
R404
F60
DOUT
R406
F60
This rung loads the data into the accumulator. This
rung executes for all channel scan or single
channel scan.
The DL305 performs math operations in BCD. This
instruction converts the binary data to BCD. (You
can omit this step if your application does not
require the data in BCD format.)
The channel selection inputs are used to let the
CPU know which channel has been loaded into the
accumulator. By using these inputs to control a
DOUT instruction, you can easily move the data to
a storage register. Notice that the DOUT
instruction stores the data in two bytes. This is
because two bytes are required to store the BCD
number.
D3–04AD
4-Channel Analog Input
Single Channel
001
002
Inputs 000 and 001 are used to select between
single channel scanning and all channel scanning.
These two points were arbitrarily chosen and could
be any permissive contacts. When output 117 is
on, all channels will be scanned.
2–14
D3–04AD 4-Channel Analog Input
The following instructions are required to scale the data. We’ll continue to use the
42.9 PSI example. In this example we’re using channel 1. Input 110 is the active
channel indicator for channel 1. Of course, if you were using a different channel, you
would use the active channel indicator point that corresponds to the channel you
were using.
This example assumes you have already read the analog data
and stored the BCD equivalent in R400 and R401
Scale the data
D3–04AD
4-Channel Analog Input
110
DSTR
R400
F50
This instruction brings the analog value (in BCD)
into the accumulator.
Accumulator
Aux. Accumulator
0 1 1 0
0 0 0 0
R577
DIV
K256
F74
The analog value is divided by the resolution of the
module, which is 256. (110 / 256 = 0.4296)
Accumulator
Aux. Accumulator
0 0 0 0
4 2 9 6
R577
DSTR
R576
F50
F73
F50
R576
The accumulator is then multiplied by the scaling
factor, which is 100. (100 x 4296 = 429600). Notice
that the most significant digits are now stored in
the auxilliary accumulator. (This is different from
the way the Divide instruction operates.)
9
DSTR
R576
R576
This instruction moves the two-byte decimal
portion into the accumulator for further operations.
Accumulator
Aux. Accumulator
4 2 9 6
4 2 9 6
R577
MUL
K100
R576
Accumulator
6 0 0
Aux. Accumulator
0 0 4 2
R577
R576
This instruction moves the two-byte auxilliary
accumulator for further operations.
Accumulator
Aux. Accumulator
0 0 4 2
0 0 4 2
DOUT
R450
F60
R577
R576
This instruction stores the accumulator to R450
and R451. R450 and R451 now contain the PSI,
which is 42 PSI.
Accumulator
Store in R451 & R450
0 0 4 2
0 0 4 2
R451
R450
2–15
D3–04AD 4-Channel Analog Input
You probably noticed that the previous example yielded 42 PSI when the real value
should have been 42.9 PSI. By changing the scaling value slightly, we can “imply” an
extra decimal of precision. Notice in the following example we’ve added another digit
to the scale. Instead of a scale of 100, we’re using 1000, which implies 100.0 for the
PSI range.
This example assumes you have already read the analog data
and stored the BCD equivalent in R400 and R401
Scale the data
110
F50
This instruction brings the analog value (in BCD)
into the accumulator.
Accumulator
Aux. Accumulator
0 1 1 0
0 0 0 0
R577
DIV
K256
F74
The analog value is divided by the resolution of the
module, which is 256. (110 / 256 = 0.4296)
Accumulator
Aux. Accumulator
0 0 0 0
4 2 9 6
R577
DSTR
R576
F50
F73
F50
R576
The accumulator is multiplied by the scaling factor,
which is now 1000. (1000 x 4296 = 4296000). The
most significant digits are now stored in the
auxilliary accumulator. (This is different from the
way the Divide instruction operates.)
6
DSTR
R576
R576
This instruction moves the two-byte decimal
portion into the accumulator for further operations.
Accumulator
Aux. Accumulator
4 2 9 6
4 2 9 6
R577
MUL
K1000
R576
Accumulator
0 0 0
Aux. Accumulator
0 4 2 9
R577
R576
This instruction moves the two-byte auxilliary
accumulator for further operations.
Accumulator
Aux. Accumulator
0 4 2 9
0 4 2 9
DOUT
R450
F60
R577
R576
This instruction stores the accumulator to R450.
R450 now contains the PSI, which implies 42.9.
Accumulator
Store in R451 & R450
0 4 2 9
0 4 2 9
R451
R450
D3–04AD
4-Channel Analog Input
DSTR
R400
2–16
D3–04AD 4-Channel Analog Input
This example program shows how you can use the instructions to load the equation
constants into data registers. The example is written for channel 1, but you can
easily use a similar approach to use different scales for all channels if required.
You may just use the appropriate constants in the instructions dedicated for each
channel, but this method allows easier modifications. For example, you could easily
use an operator interface or a programming device to change the constants if they
are stored in Registers.
Load the constants
D3–04AD
4-Channel Analog Input
374
Read the data
374
Store channel 1
110
On the first scan, these first two instructions load
the analog resolution (constant of 256) into R430
and R431.
DSTR
K256
F50
DOUT
R430
F60
DSTR
K1000
F50
DOUT
R432
F60
DSTR1
R001
F51
This rung loads the data into the accumulator on
every scan. (You could use any permissive contact.)
BCD
F86
The DL305 CPUs perform math operations in
BCD. Since we will perform math on the data, the
data must be converted from binary data to BCD.
DIV
R430
F74
The analog value is divided by the resolution of the
module, stored in R430.
DSTR
R576
F50
This instruction moves the decimal portion from the
auxilliary accumulator into the regular accumulator
for further operations.
MUL
R432
F73
The accumulator is multiplied by the scaling factor,
stored in R432.
DSTR
R576
F50
This instruction moves most significant digits (now
stored in the auxilliary accumulator) into the
regular accumulator for further operations.
DOUT
R400
F60
The scaled value is stored in R400 and R401 for
further use.
These two instructions load the high limit of the
Engineering unit scale (constant of 1000) into
R432 and R433. Note, if you have different scales
for each channel, you’ll also have to enter the
Engineering unit high limit for those as well.
2–17
D3–04AD 4-Channel Analog Input
Writing the Control Program (DL350)
Multiplexing:
DL350 with a
Conventional
DL305 Base
The example below shows how to read multiple channels on an D3–04AD Analog
module in the 10–17/110–117 address slot. This module must be placed in a 16 bit
slot in order to work.
Load the data
_On
SP1
X10
This rung loads analog data and converts it to
BCD.
K8
BCD
(
X117
OUT
)
When X117 is On, all channels will be scanned.
Store Channel 1
X110
OUT
This writes channel 1 analog data to V3000 when
bit X110 is on.
V3000
Store Channel 2
X111
OUT
V3001
This writes channel 2 analog data to V3001 when
bit X111 is on.
Store Channel 3
X112
OUT
V3002
This writes channel 3 analog data to V3002 when
bit X112 is on.
Store Channel 4
X113
OUT
V3003
This writes channel 4 analog data to V3003 when
bit X113 is on.
D3–04AD
4-Channel Analog Input
LDF
2–18
D3–04AD 4-Channel Analog Input
Multiplexing:
DL350 with a
D3–xx–1 Base
The example below shows how to read multiple channels on an D3–04AD Analog
module in the X0 address of the base. If any expansion bases are used in the
system, they must all be D3–xx–1 to be able to use this example. Otherwise, the
conventional base addressing must be used.
Load the data
_On
SP1
LDF
X0
This rung loads analog data and converts it to
BCD.
D3–04AD
4-Channel Analog Input
K8
BCD
(
X17
OUT
)
When X17 is On, all channels will be scanned.
Store Channel 1
X10
OUT
This writes channel 1 analog data to V3000 when
bit X10 is on.
V3000
Store Channel 2
X11
OUT
V3001
This writes channel 2 analog data to V3001 when
bit X11 is on.
Store Channel 3
X12
OUT
V3002
This writes channel 3 analog data to V3002 when
bit X12 is on.
Store Channel 4
X13
OUT
V3003
This writes channel 4 analog data to V3003 when
bit X13 is on.
2–19
D3–04AD 4-Channel Analog Input
Scaling the Input
Data
Most applications usually require
measurements in engineering units,
which provide more meaningful data.
This is accomplished by using the
conversion formula shown.
Units = (A/255)*S
Units = value in Engineering Units
A = Analog value (0 – 255)
S = Engineering unit range
Units = (A/255)*S
Units = (110/255)*100
Units = 43
Here is how you would write the program to perform the engineering unit conversion.
This example assumes you have the analog data in BCD format data loaded into
V3000.
NOTE: This example uses SP1, which is always on. You could also use an X, C, etc. permissive contact.
SP1
LD
V3000
When SP1 is on, load channel 1 data to the accumulator.
MUL
K100
Multiply the accumulator by 100 (to start the conversion).
DIV
K255
Divide the accumulator by 255.
OUT
V3010
Store the result in V3010.
D3–04AD
4-Channel Analog Input
The following example shows how you
would use the analog data to represent
pressure (PSI) from 0 to 100. This
example assumes the analog value is
110, which is slightly less than half scale.
This should yield approximately 43 PSI.
2–20
D3–04AD 4-Channel Analog Input
Analog and Digital Sometimes it is helpful to be able to quickly convert between the signal levels and the
Value Conversions digital values. This is especially helpful during machine startup or troubleshooting.
The following table provides formulas to make this conversion easier.
Range
D3–04AD
4-Channel Analog Input
1 to 5V
4 to 20mA
If you know the digital value ...
If you know the analog signal
level ...
A = (4D/255) + 1
D = (255/4)(A–1)
A = (16D/255) + 4
D = (255/16)(A–4)
For example, if you are using the 1 to 5V
range and you have measured the signal
at 3V, you would use the following
formula to determine the digital value
that should be stored in the register
location that contains the data.
D = (255/4)(A–1)
D = (255/4)(3V–1)
D = (63.75) (2)
D = 127.5 (or 128)
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertisement