Mitsubishi MELSEC Q Series User Manual

10 - 15
10.2 Programming Using Bus Interface Functions
10.2.4 Programming using bus interface functions
10
FUNCTIONS AND PROGRAMMING
(2) Precautions for using the bus interface functions
(a) Programming precautions
1) Open/close processing
Perform the bus open/close (QBF_Open function/QBF_Close function)
processing only once at the beginning and end of the program.
Communication performance will decrease if open/close is repeated at each
communication.
2) Simultaneous processing of bus interface functions
The bus interface functions cannot be used for simultaneous processing of
multiple tasks in the C Controller module.
If processings by the bus interface functions is requested simultaneously by
multiple tasks, the bus interface function processing requested by one task
waits until the other task completes the processing of the bus interface
function.
3) User watchdog timer error interrupt
When using the bus interface functions on multiple tasks, register the user
watchdog timer error interrupt from one of the tasks.
4) Clock setting
When setting the clock of the C Controller module, make setting without the
QBF_WaitEvent function and QBF_WaitUnitEvent function being executed.
5) Remote STOP/PAUSE and bus interface function execution result
When the operation status of the C Controller module is remote STOP or
remote PAUSE, the execution result of the following operation by the user
program is a STOP/PAUSE error.
• Output (Y) (QBF_Y_OutBitEx function, QBF_Y_OutWordEx function)
• Buffer memory writing (QBF_ToBuf function)
Y output and buffer memory writing can be executed from the <<Module
monitor>> tab of the C Controller setting utility.
(b) Precautions for self station device access via CC-Link module
When making access via a CC-Link module, create the user program so that
interlocks are provided to validate data write/read to/from the self station device.
Data become valid only when the following conditions are satisfied.
• Module error (Xn0) is OFF (Normal)
• Module ready (XnF) is ON (Operable)
• Self data link status (Xn1) is ON (In data link)
Even if the above conditions are not satisfied, however, write to/read from the self
station is normally terminated.

Mitsubishi MELSEC Q Series Specifications

General

Brand	Mitsubishi
Model	MELSEC Q Series
Category	Controller
Language	English