Engineering Unit Conversion - Automation Direct DL405 User Manual

Here is how you would write the program to perform the engineering unit
conversion. This example assumes you have calculated or loaded the engineering
unit value and stored it in V3000. Also, you have to perform this for all eight
channels if you are using different data for each channel.
NOTE: The DL405 offers various instructions that allow you to perform math
operations using binary, BCD, etc. It's usually easier to perform any math
calculations in BCD and then convert the value to binary before you send the data to
the module. If you are using binary math, you do not have to include the BIN
conversion.
X1
V-Memory The ladder program examples that follow occasionally use certain V-memory
Registers register addresses in the CPU that correspond to 16-bit Y output modules. Use the
table below to find the V-memory address for the particular slot of your analog
module. See Appendix A for additional addresses available in the DL450 CPU.
Y
V 40500 40501 40502 40503 40504 40505 40506 40507 40510 40511
Y
V 40512 40513 40514 40515 40516 40517 40520 40521 40522 40523
When X1 is on, the engineering units (stored in V3000) are loaded
LD
into the accumulator. This example assumes the numbers are BCD.
V3000
Multiply the accumulator by 4095 (to start the conversion).
MUL
K4095
Divide the accumulator by 1000 (because we used a multiplier of 10,
DIV
we have to use 1000 instead of 100).
K1000
Convert the BCD number to binary.
BIN
Store the result in V3101. This is the digital value, in binary form, that
OUT
should be sent to the module.
V3101
V-Memory Register Addresses for 16-Point Output (Y) Locations
000 020 040 060
240 260 300 320
F4–08DA–1 8-Ch. Analog Current Output
100 120 140
340 360 400
15–11
160 200 220
420 440 460