5: S
PECIAL
F
UNCTIONS
FC5A M
ICRO
S
MART
U
SER
’
S
M
ANUAL
FC9Y-B1268
5-23
Clearing High-speed Counter Current Value
The high-speed counter current value is reset to the reset value (two-phase high-speed counter) or to zero (single-phase
high-speed counters) in five ways:
when the CPU is powered up,
when a user program is downloaded to the CPU,
when reset input I2 (HSC1) or I5 (HSC4 on slim type CPU only) is turned on,
when current value overflow or underflow occurs (two-phase) or when the preset value is reached (single-phase when
Keep Current Value is not selected), or
when the reset input (
not
the high-speed counter reset input) designated in the Function Area Settings is turned on.
Precautions for Downloading High-speed Counter Program
When downloading a user program containing a high-speed counter, turn off the gate input before downloading the user
program.
If a user program containing a high-speed counter is downloaded while the gate input is on, the high-speed counter is
disabled. Then, to enable counting, stop and restart the
MicroSmart
. Or, turn off the gate input, and 3 scans later turn on
the gate input again. For ladder programs to delay the gate input 3 scans, see pages 5-27 and 5-29.
Preset Values 1 and 2
Preset values 1 and 2 take effect in the END processing at the end of the second scan after starting the CPU module. Use
initialize pulse special internal relay M8120 to store preset values to appropriate data registers.
If preset value 1 or 2 has been changed during high-speed counter operation, the new preset value takes effect when the
current value reaches the previous preset value. To change preset values easily, store new preset values in an interrupt
program and call the new preset values when the current value reaches the previous preset value.
Phone: 800.894.0412 - Fax: 888.723.4773 - Web: www.clrwtr.com - Email: [email protected]
