Table of Contents
Advertisement
Counters
Feature
Count direction
Setpoint value
range
Setpoint value entry
Counter overflow
behaviour
Counter output
Resetting
In addition to normal counters the controllers of the MELSEC FX family also have high-speed
counters. These are 32-bit counters that can process high-speed external counter signals
read on inputs X0 to X7. In combination with some special instructions it is very easy to use
these counters to automate positioning tasks and other functions.
High-speed counters use an interrupt principle: The PLC program is interrupted and responds
immediately to the counter signal. For a detailed description of high-speed counters please
refer to the Programming Manual for the MELSEC FX family.
4 – 10
16 Bit Counters
Incrementing
1 to 32767
Directly as a decimal constant (K) in the
instruction, or indirectly in a data register
Counts to a maximum of 32,767, after which
the counter value no longer changes.
Once the setpoint value has been reached
the output remains on.
An RST instruction is used to delete the current value of the counter and turn off its output.
Devices in Detail
32 Bit Counters
Incrementing and decrementing (the direc-
tion is specified by switching a special relay
on or off)
-2 147 483 648 to 2 147 483 647
Directly as a decimal constant (K) in the
instruction or indirectly in a pair of data
registers
Ring counter: After reaching 2,147,483,647
the next incrementing value is
-2,147483,648. (When counting backwards
the jump is from -2,147483,648 to
2,147,483,647)
When incrementing the output remains on
once the setpoint value has been reached.
When decrementing the output is reset
(switched off) once the value drops below
the setpoint value.
MITSUBISHI ELECTRIC
Advertisement
Table of Contents
