Rockwell Automation 1771-QRD PULS FLOWMTR - Manual (Page 35)

More on Overrange and Overflow
Chapter 5
5–3
Any or all of the totalizers and overflow flags can be reset using a Block
Transfer Write command sent to the 1771–QRD from the PLC. For a
PLC–5 processor, the rung might look like this:
The Block Transfer Write sends the 1771–QRD one word that contains the
correct bit pattern to reset the totalizer(s) and/or overflow flags. The BTW
data word can be changed through the ladder logic, or by editing the data
table.
Note that the Block Transfer Write is switch selectable, and its length is
one word. The block transfer should only be sent once unless the ladder
intelligently sets and clears the reset bits within the Block Transfer data. As
an example, the ladder might set the reset bit at the time of overflow. If the
Block Transfer is sent continuously and the reset bits contained within the
Block Transfer data are simply left set to “1”, the transfers will constantly
be resetting the totalizer(s) and/or overflow flags of the specified channels.
The word from the block transfer data table would appear in the DATA
MONITOR as:
N41:0 00XX
Where: “XX” are the 8 bits used to reset the totalizer(s) and/or overflow bits.
Breaking down the word in the data table into binary format:
N41:0 0000 0000 XXXX XXXX
4 3 2 1 4 3 2 1
To reset overflow flags To reset totalizers
The numbers underneath the “X” ’s are the channel numbers that are
affected when the corresponding bit is a “1”. Note that a “1” resets the
totalizer(s) and/or overflow bits, and a “0” leaves them unchanged.
NOTE: Resetting the totalizer(s) will automatically reset its respective
overflow flag(s).
Using A Block Transfer Write
to Reset the Totalizer(s)
and/or Overflow Flags