Rockwell Automation 1771-N SERIES High Resolution Analog Module User Manual - Manual (Page 43)

4–3 Configuring the Module
Publication 1771ĆUM127B-EN-P - December 2002
Module level programming features include:
• module “configuration” verification
• temperature scale
• data format
• real time sample
Module Configuration" Verification
The verify bit 00 in the block transfer write word 3 allows you to
compare the configuration information the module is using to the
configuration information contained in a block transfer write (BTW).
You set the verify bit in the BTW you wish to check, and download
the BTW to the module. After the BTW is completed, request a BTR
from the module. The program verify field in the BTR (bits 09-10
decimal, bits bits 11-12 octal, word 1) will contain either of two
values: 10 (binary) indicates the verify failed; 11 (binary) indicates
the verify succeeded.
If the verify bit is set, configuration information in the BTW data file
will not be used by the module regardless of the success or failure of
the verify.
Temperature Scale
You select the temperature scale that the module will use when
returning temperature to the processor using bit 01, word 3 of the
block transfer write data file. If the bit is set to 0, the temperature is
in degrees C; if the bit is set to 1, the temperature is in degrees F.
Data Format
Use bit 02, word 3 of the block transfer write data file to select a data
format. If this bit is 0, all data fields will be in two’s complement
binary format. If the bit is 1, all fields will be in BCD format. In
BCD, the most significant bit is the sign bit for all signed fields. This
sign bit applies to both BTW and BTR words.
NOTE: Available resolution is poor when using BCD format.
The 4-digit BCD format uses an arrangement of 16 binary digits to
represent a 4-digit decimal number from 0000 to 9999 (Figure 4.1).
The BCD format is used when the input values are to be displayed
for operator viewing. Each group of four binary digits is used to
represent a number from 0 to 9. The place values for each group of
digits are 2
0 , 2 1 , 2 2 and 2 3 (Table 4.A). The decimal equivalent for a
group of four binary digits is determined by multiplying the binary
digit by its corresponding place value and adding these numbers.
Module Level
Programming Features