Rockwell Automation 1761 MicroLogix 1000 Programmable Controllers - Manual (Page 191)

Using Application Specific Instructions
11–3
Bit Shift Instructions Overview
The following general information applies to bit shift instructions.
Entering Parameters
Enter the following parameters when programming these instructions:
•
File is the address of the bit array you want to manipulate. You must use the
file indicator (#) in the bit array address.
•
Control is the address of the control element that stores the status byte of the
instruction, the size of the array (in number of bits). Note that the control
address should not be used for any other instruction.
The control element is shown below.
EN DN ER UL Not used
15 13 11 10 00
Size of bit array (number of bits)
Reserved
Word 0
Word 1
Word 2
Status bits of the control element may be addressed by mnemonic. They
include:
– Unload Bit UL (bit 10) is the instruction’s output.
– Error Bit ER (bit 11), when set, indicates the instruction detected an error
such as entering a negative number for the length or position. Avoid using
the unload bit when this bit is set.
– Done Bit DN (bit 13), when set, indicates the bit array shifted one
position.
– Enable Bit EN (bit 15) is set on a false-to-true transition of the rung and
indicates the instruction is enabled.
When the register shifts and input conditions go false, the enable, done, and
error bits are reset.
Programming