Chapter 2 Devices
2-47
There are 2048 stepping relays, i.e. S0~S2047. Every stepping relay is like an output relay in that it
has an output coil, contact A, and contact B. It can be used several times in the program, but it can
not directly drive the external load. Besides, the stepping relay can be used as a general auxiliary
relay when it is not used in the sequential function chart.
2.2.10 Timers
1. 100 millisecond timer: The timer specified by the instruction TMR takes 100 milliseconds as the
timing unit.
2. 1 millisecond timer: The timer specified by the instruction TMRH takes 1 millisecond as the
timing unit.
3. The timers for the subroutine’s exclusive use are T1920~T2047.
4. The accumulative timers are ST0~ST2047. If users want to use the device-monitoring function,
they can monitor T0~T2047.
5. If the same timer is used repeatedly in the program, including in different instructions TMR and
TMRH, the setting value is the one that the value of the timer matches first.
6. If the same timer is used repeatedly in the program, it is OFF when one of the conditional
contacts is OFF.
7. If the same timer is used repeatedly in the program as the timer for the subroutine’s exclusive
use and the accumulative timer in the program, it is OFF when one of the conditional contacts
is OFF.
8. When the timer is switched from ON to OFF and the conditional contact is ON, the timer is reset
and counts again.
9. When the instruction TMR is executed, the specified timer coil is ON and the timer begins to
count. As the value of the timer matches the setting value, the state of the contact is as follows.
Normally open (NO) contact
Normally closed (NC) contact
A. The general-purpose timer
When the instruction TMR is executed, the general-purpose timer begins to count. As the value
of the timer matches the setting value, the output coil is ON.
When X0.0 is ON, the timer T0 takes 100 milliseconds as the timing unit and counts up. As
the current value of the timer matches the setting value 100, the output coil of T0 is ON.
When X0.0 is OFF or there is a power cut, the current value of the timer is reset to 0 and the
output coil is switched OFF.
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