Specifications

15PROFINET Controller ME1PN1FW-Q

handshake mechanism exists to ensure consistency on all variables. This mechanism is optional

and can be activated and deactivated per device.

Input and Output Data Alignment

The IO-device input and output areas in the buffer memory of the PROFINET Controller are word-ali-

gned. PROFINET variables are located in the shared memory by respecting the following rules

The data of each PROFINET IO-device is placed at an address on a word boundary, independent

of its type.

Single or array variables must be aligned on an address modulo of the minimum of both the PLC

alignment (2) and the native type size (1, 2 or 4). So specifically

o Each slot should always be located at the next available word boundary address

o BYTEs or BYTE ARRAYS of the same slot are packed in memory to follow directly the previous

defined variable

o WORDs should always be located at the next available word boundary address

o DWORDs, FLOATs should be also located at a word boundary address

Additionally all WORD, DWORD and FLOAT variables are stored in little-endian format in shared me-

mory, to ease interpretation of the variables by the PLC program.

Example:

IO-Device Consistency Management (IOD_CONSIST Registers)

The Q-series OS can ensure data consistency within a word in the data exchange via Autorefresh.

The Autorefresh settings of the respective module contain a module specific X-device, which the

communication module resets during access to the buffer memory. The CPU must check this device

before accessing the buffer memory. If consistency handling has been disabled in the module, the

device remains permanently set. The single X-device can only control access to the I/O data of all

slaves together. An individual handshake for each station is not possible with this approach.

Using the following 128 bits the PLC can enable and disable at any time the consistency manage-

ment per device.

From CPU to PROFINET IO-Controller

Global Variable Identifiers

IO-Device

Number

Values

0 (default)

vPN_MGMT_OUTPUTS.IOD_CONSIST[0]

…

vPN_MGMT_OUTPUTS.IOD_CONSIST[15]

Disable Con-

sistency

Enable Con-

sistency