AB Quality Allen-Bradley 1771-IJ, Руководство пользователя

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6–3 Block Transfer Programming
Publication 1771ĆUM006B-EN-P - June 2002
The module indicates it has reset its count to zero by setting the
home bit (bit 17 in the input status word). It resets this bit when the
home latch enable bit (bit 04) is reset. (Refer to Figure 4.2, Input
Status Word).
The system can bring the machine back to a repeatable starting
position, and the module count can be reset to zero by toggling either
the market input or home limit switch rather than changing bits 01
and 00 in the control word as long as the three conditions are met.
Carry and borrow bits are not affected by resetting the module count.
The home limit switch LED turns on whenever the home limit
switch is closed.
Bit 03 of this word is the up/down bit. This bit is significant only
when the module is used in the counter mode. The state of this bit
control module function as follows:
1 -The module increments its accumulated count with each pulse
received on Channel A.
0 -The module decrements its accumulated count with each pulse
received on channel A.
Note that if a device is wired to the Channel B input of the module
for external count direction, the up/down bit must be set to 1.
Bit 02 is the enable outputs bit. The status of this bit controls
module outputs as follows:
1 -Outputs enabled. This means that the outputs of the module can
be energized based on logical operations performed by the module.
0 -Outputs disabled. This means that the outputs of the module
cannot be energized.
With bit 02 set to 1, the module can energize its output terminals
based on a comparison of its accumulated count and preset values
entered by the program.
Bits 00 and 01 are termed function control bits. These bits control
module function in both encoder and counter modes. They permit
the counting function of the module to be enabled or reset by the
program. The table in Figure 6.1 shows the bit settings for each
function.
Bits 05-17 of this word are not used by the module and may have
any setting.