Rockwell Automation 1761 MicroLogix 1000 Programmable Controllers - Manual (Page 234)

Preface MicroLogix 1000 Programmable Controllers User Manual
12–20
The high-speed counter hardware is updated immediately when the HSL instruction
is executed regardless of high-speed counter type (Up Counter or Bidirectional
Counter). For the Up Counters, the last two registers are ignored since the low
preset does not apply.
If a fault occurs due to the HSL instruction, the HSL parameters are not loaded to
the high-speed counter hardware. You can use more than one HSL instruction in
your program. The HSL instructions can have different image locations for the
additional parameters.
Do not change a preset value and an output mask/source with the same HSL
instruction as the accumulator is approaching the old preset value.
If the high-speed counter is enabled and the HSL instruction is evaluated true,
the high-speed counter parameters in the HSL instruction are applied
immediately without stopping the operation of the high-speed counter. If the
same HSL instruction is being used to change the high-speed counter
controlled mask/source and the preset, the mask/source is changed first and
the preset second. (The preset is changed within 40
µ
s after the mask/source.)
If the original preset is reached after the new mask/source is applied but
before the new preset is applied, the new outputs are applied immediately.