FX Series Programmable Controllers | Devices in Detail 4 |
4.9.1General timer operation
Timers operate by counting clock pulses (1, 10 and 100 msec). The timer output contact is activated when the count data reaches the value set by the constant K. The overall duration or elapsed time, for a timers operation cycle, is calculated by multiplying the present value by the timer resolution, i.e.
A 10 msec timer with a present value of 567 has actually been operating for: 567× 10 msec
567× 0.01 sec = 5.67 seconds
Timers can either be set directly by using the constant K to specify the maximum duration or indirectly by using the data stored in a data register (ex. D). For the indirect setting, data registers which are battery backed/ latched are usually used; this ensures no loss of data during power down situations. If however, the voltage of the battery used to perform the battery backed service, reduces excessively, timer malfunctions may occur.
4.9.2Selectable Timers
FX1S
FX1N 
FX2N 
FX2NC
On certain programmable controllers, driving a special auxiliary coil redefines approximately half of the 100 msec timers as 10 msec resolution timers. The following PLC’s and timers are subject to this type of selection.
-For FX1S, driving M8028 ON, timers T32 to 62 (31 points) are changed to 10 msec resolution.
Driving special auxiliary coils:
• Please check the definition of special auxiliary coils before using them. Not all PLC’s associate the same action to the same device.
