Q4ARCPU - Programmable controller - MITSUBISHI

■ High speed processing

The requirement for faster processing speed of PLC systems will never end because faster processing means shorter production time, more precise control, and better quality in applications. MSP (Mitsubishi Sequence Processor) performance has been greatly improved compared to the types used in AnA/AnUCPU. QnACPUs gives roughly 3 times faster processing speed than AnUCPUs.

■ Large built-in memory and optional IC card

Each CPU module is equipped with a large built-in memory in addition to approximately 30k words of internal device memory. With the largest memory available, the Q4A and Q4ARCPU can control up to a 124k step program.

■ Global and local devices

MELSEC-QnA offers a new concept in internal device memory. In support of the multiple programming features of QnA PLCs, each program module can be installed with its own internal memory bank, called a ‘local device.’ The data of the local device does not influence the results of other program modules, and conversely it is not affected by other modules either. Local devices, then, can be used freely within program modules. At the same time, global devices with a common memory shared by all the program modules are also available, and can be used for interlocking of program modules

■ Multiple programs

Up until now, PLC programs were generally composed of one long program which handled all tasks, but because of PLC’s scanning operation and program size, programming and debugging was not easy. Even utilization of a previously made program for another control application was not easy to implement. MELSEC QnA can handle and execute multiple program modules. At the program design stage, program modules can be created process by process, function by function (e.g. of a machine) or designer by designer for concurrent design. There are many advantages to this approach.

●Easier to understand because each program module can be made for specific functions and program modules are smaller than one long program.

●Program merging is not necessary after parallel design of program modules by multiple designers.

●Easier to make standardized program modules which can be used repeatedly for other similar projects.

●Saves time for program up/down loading at debugging stage because of smaller program size.

■ Q6MEM Series IC memory card

Q6MEM are PCMCIA compatible IC memory cards that can extend the data memory size of the CPU. There are a number of memory sizes and types that can be chosen based on application requirements. Up to 2MB per card is available in the following formats: SRAM memory only, SRAM+ EEPROM and Flash ROM+SRAM. Although an IC memory card is optional, it is required if the following apply.

●Sampling trace, Program trace, or Status latch function is used

●More than 16 fault records are required

●Store device comment in CPU

●File registers are required

●Local device function is used

●Program-boot from IC card is required

●Max. size of program (depending on CPU type) is created

■ Macro command

A ladder program block used frequently in a given program can be registered as a macro command and then utilized in any other program any number of times with different input and output devices. Use of this feature eliminates retyping of the same form of ladder block and helps standardize programming. Pre-registered macro command libraries are also available. The macro library software SWMIVD-MSPQ/MSDQ consists of the following macro commands: The special function module library MSPQ comprises ladder program blocks necessary for MELSEC special function modules such as the RS232C interface module. The standard ladder program library MSDQ comprises ladder blocks generally required for machine controls such as on-delay timers and emergency stop detection