Module Access Device; Precautions - Mitsubishi Electric MELSEC iQ-R Series User Manual

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Module Access Device

This device directly accesses from the CPU module to the buffer memory of the intelligent function module mounted on the

main base unit and extension base unit.

Specify this device with 'Un\Gn'. (Example: U5\G11)

Specified item

When reading/writing the buffer memory data using the module access device more than twice within a

program, the processing speed can be increased by conducting read/write operations at a single point of the

program using the FROM/TO instruction.

• When data is written using more than one module access device:

• When data is written at a single point of the program using the TO instruction:

(1) Store data to devices such as the data register (D).

(2) Write data to only one point in the program.

The following describes the precautions for when the module access device is used.

• If data is written to the refresh-target memory using a program while the refresh function is being used, the CPU module

overwrites the data in the target memory at the execution of the refresh function. Thus, the expected operation may not be

acquired. When the refresh function is used, do not write the data directly to the refresh-target memory but write it to the

refresh-source memory.

*1 When the data is transferred from the CPU module to the module, the target memory is the buffer memory or link device. When the data

is transferred from the module to the CPU module, the target memory is the specified device of the CPU module.

27.6 Module Access Device

Start I/O number of intelligent function modules

Buffer memory address

Value to be specified

Upper two digits when a start I/O number is described in three digits

(00H to FFH)

Example: 1F stands for X/Y1F0

0 to 268435455 (decimal)