Rockwell Automation 1771-OFE/B Analog Output Module User Manual - Manual (Page 31)

3-5
Publication 1771Ć6.5.30 - November 1998
Some examples of how to determine the value of the data word
needed to produce the desired output voltage or current follow:
Output Range 4Ć20mA
Data Format BCD (0Ć4095)
Desired Output 9.5mA
D I/Bit 0.0039mA/Bit (from Table 3.B)
Remember, 4mA corresponds to scale minimum
(9.5mA Ć 4mA)
0.0039mA/Bit
@ 1410 (decimal) = 0001 0100 0001 0000 (BCD)
Example 1
You would enter 1410 (BCD) or 0001 0100 0001 0000 into the data
word in order to get an output of 9.5 mA.
Output Range 0Ć10V
Data Format 12Ćbit binary (0ĆFFF)
Desired Output 9.0V
D I/Bit 2.44mV/Bit (from Table 3.B)
9.0V
2.44mV/Bit
@ 3689 (decimal) = 0000 1110 0110 1001 (binary)
Example 2
You would enter 0000 1110 0110 1001 into the data word to get an
output of 9.0V.
These values are loaded into the module’s memory, from the
processor, with a block transfer write.
Important: If you are using BCD data format, you must download
values to the module in the BCD format and set the
corresponding data polarity bit (see Figure 3.1) if a
negative output is desired.
Important: If the binary data format is selected, data can be
downloaded in a binary or 2’s complement binary data
format. If binary is used, the appropriate data polarity
bit must be set to express a negative value. The 2’s
complement format expresses a negative value via the
bit pattern.
If the processor input information governs the module’s outputs,
remember that data written to the output module must fall within
certain limits. Both BCD and binary data must fall within the range
+9999. You can use the negative ranges by setting the “negative
data” bits in word 5 of the BTW.