User`s manual

Features of the MELSEC System Q Basics
MELSEC System Q, Hardware 2 – 3
High speed program processing
CPU types with an additional "H" (like Q12HCPU, Q25HCPU or Q12PHCPU) do a faster
processing of the program. The operation time for the LD instruction (load) by the Q02CPU is
79 ns. The same instruction is done in 34 ns by the H type CPU.
An universal model PLC CPU increases the processing speed additionally. The operation time
of the above mentioned LD instruction takes only 20 ns with the Q03UDCPU and only 9.5 ns with
CPU modules from Q04UDCPU on.
With the new MELSEC System Q main base units with integrated memory and processor the
data transfer to I/O modules, intelligent function modules and network modules is much faster
compared to the previous base units. The access of the Q02HCPU to an intelligent function
module is with 20 µs per word 7 times faster than with the Q2ASHCPU. The refresh cycle of the
MELSECNET/10 network is around 4.3 times faster compared to the Q02HCPU and needs only
4.6 ms for 8 kwords.
Multi CPU operation
Except Q00JCPU all CPU modules of System Q are suitable für multi-CPU operation. Up to four
CPU modules can be mounted on one main base unit to which the mounted I/O and intelligent
function modules are assigned. The data transfer between the CPU modules can run automat-
ical and cyclic. Also mixed configurations are possible with PLC CPU, Motion Controller CPU
and Q PC. But Q00CPU and Q01CPU can’t be combined with H type CPUs.
By multi-CPU operation the cycle time is decreased, the performance is increased and the appli-
cation is wider.
Redundant operation
The operation of a redundant system is continued, even if single components have a failure. This
in
creases performance and outage and shutdown times are minimized.
The redundant PLC of MELSEC System Q consists of two controllers with identical configura-
tions (power supply, Q12PRHCPU or Q25PRHCPU, network modules, etc.), which are con-
nected by a so called tracking cable. One PLC controls the system, while the other one is in
standby mode. In case of an error the system switches from the control system to the standby
system and the process continues without any interruption.
Also a PLC with a standard CPU can be protected with two redundant power supplies against
failures. Therefore a main base unit and an extension base unit with two types of power supply
are available, one with 24 V DC input and one with 100–240 V AC input.
Range of instructions
Instructions for a Q-CPU are divided into two categories, basic instructions and comprehensive
dedicated instructions. The process CPUs and redundant CPUs have additionally 52 process
control instructions. Therefore these CPU types are particularly suitable for applications of proc-
ess technology.
The capacity for the PLC programm is between 8 and 252 k steps depending on the CPU type.