Delta MH300 Series - Page 881

Chapter 16 PLC Function ApplicationsMH300
16-18
Device
Type
Description of Function
Counter
Counters perform counting operations. The setting value for a counter (such as the number
of pulses to be counted) must be assigned when a counter is used. A counter contains a
coil, contact, and a counting storage device. When the coil goes from OFF
ON, this
indicates that the counter receives an input pulse, and adds one to its count. There are 16
bits available in the counter.
 Counter device is indicated by: C0, C1–C79, and so on. These devices
are indicated
by the symbol C, and the device’s order is indicated with a decimal number.
Timer
Timers perform timing for operations. The timer contains a coil, contact, and a time value
register. When the coil is electrified, and the setting value for t
he timer is reached, the
contact is actuated (contact A closes, contact B opens), and the timer’
s fixed value is given
by the setting value. A timer has a regulated clock cycle (timing units: 100 ms). As soon as
power to the coil is cut off, the contact is
no longer be actuated (contact A opens, contact
B closes), and the original timing value returns to zero.
 Timer devices are indicated by: T0, T1–
T159, and so on. These devices are indicated
by the symbol T, and the device’s order is indicated with a decimal number.
Data
Register
Data registers are used exclusively to store data and various parameters. When you use a
PLC is to perform various types of sequence control, set time values, and count value
controls, the PLC performs data processing and numerical operations and stores th
e
operands, parameters, and results in data registers. Each data register contains 16 bits of
binary data (one word). Two data registers with adjacent numbers can process double
words.
 Data register devices are indicated by: D0, D1–D399, and so on. These
devices are
indicated by the symbol D, and the device’
s order is indicated with a decimal number.
Ladder diagram images and explanations
See the Section 16-4-2 “Introduction to ladder diagrams” for descriptions of devices.
Ladder diagram
structures
Explanation of commands Command Using Device
N.O. switch, contact A LD X, Y, M, T, C
N.C. switch, contact B LDI X, Y, M, T, C
Series N.O. AND X, Y, M, T, C
Series N.C. ANI X, Y, M, T, C