Allen-Bradley MicroLogix 1200 Reference Manual page 94

5-24 Using the High-Speed Counter
Table 5.12 Affect of HSC Output Mask on Base Unit Outputs
Output Address
HSC:0.HPO (high preset output)
HSC:0.OMB (output mask)
O0:0.0
Publication 1762-RM001C-EN-P
Output Mask Bits (OMB)
Description Address
OMB - Output Mask Bits HSC:0.OMB
The OMB (Output Mask Bits) define which outputs on the controller can
be directly controlled by the high-speed counter. The HSC sub-system has
the ability to directly (without control program interaction) turn outputs
ON or OFF based on the HSC accumulator reaching the High or Low
presets. The bit pattern stored in the OMB variable defines which outputs
are controlled by the HSC and which outputs are not controlled by the
HSC.
The bit pattern of the OMB variable directly corresponds to the output
bits on the controller. Bits that are set (1) are enabled and can be turned
on or off by the HSC sub-system. Bits that are clear (0) cannot be turned
on or off by the HSC sub-system. The mask bit pattern can be configured
only during initial setup.
The table below illustrates this relationship:
16-Bit Signed Integer Data Word
15 14 13 12 11 10 9
The outputs shown in the black boxes are the outputs under the control
of the HSC sub-system. The mask defines which outputs can be
controlled. The high preset output or low preset output values (HPO or
LPO) define if each output is either ON (1) or OFF (0). Another way to
view this is that the high or low preset output is written through the
output mask, with the output mask acting like a filter.
The bits in the gray boxes are unused. The first 12 bits of the mask word
are used and the remaining mask bits are not functional because they do
not correlate to any physical outputs on the base unit.
The mask bit pattern can be configured only during initial setup.
Data Format Type
word (16-bit binary) control read only
8 7 6
0 1 1 0 1 0
1 0 0 0 0 1
0 0
User Program Access
5 4 3 2 1 0
0 1 1 0 0 1
1 1 0 0 1 1
0 1 0 1