Technical data

Addressing I/Os

You can use load and transfer operations to address the I/O

peripherals as follows:

•• directly using the following operations:

L../T.. ..PY, ..PW, ..OY, ..OW

•• using the process image with the following operations:

L../T.. ..IB, ..IW, ..ID, .QB, ..QW, ..QD

and with logic and set/reset operations

Note

If you use the transfer operations T PY 0 to 127 and T PW 0 to

126, the process output image is updated at the same time.

Exception: command output is disabled by the STEP 5 operation

BAS (refer to Section 3.5.4).

Note the following points about I/O peripherals:

•• A process input/output image exists for 128 input and 128 output

bytes of the P peripherals with byte addresses from 0 to 127.

•• No process image exists for the entire area of the O peripherals

and the P peripherals with relative byte addresses from 128 to 256.

(For more information on address space allocation see

Section 8.2.2).

•• I/O modules with addresses of the O peripherals can only be

plugged into expansion units (not in the central controller).

•• In one expansion unit, you can use either only P peripherals or

only O peripherals.

Caution

If you use relative addresses of the O peripherals in an expansion

unit, you can no longer use these addresses for I/O modules in the

central controller (this would result in double addressing).

Basic Operations

CPU 928B Programming Guide

C79000-B8576-C898-01

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