User`s manual

349

CHAPTER 15 SWITCHING THE MODE AFTER STARTING

15.2 Mode Switching Precautions

(1) Set-up between the external device and the programmable controller CPU

Make the following setting for the external device and the programmable controller CPU so that mode switching

is not performed during data communications.

(a) Which side is to switch the mode, the programmable controller CPU or external

device

(b) Timing for each mode switching pattern

(For mode switching patterns,  Page 345, CHAPTER 15.)

• Method and message structure when all the connected stations are informed of the mode switching

execution

• Method and message structure when all the connected stations are informed of the mode switching

completion

• Device No. and meaning of the value when a programmable controller CPU word device is used

(2) Mode switching from external device

(a) Once the mode has been changed to a mode other than MC protocol (Formats 1 to

5), it cannot be changed from the external device.

In this case, change the mode on the programmable controller CPU.

(b) Only the Q series C24 (including multidrop link stations) connected to an external

device is available for mode switching from the external device

( MELSEC Communication Protocol Reference Manual)

It is not available for other Q series C24 stations connected over a network system.

It is recommended to switch the mode on the programmable controller CPU side.

(3) Data communications after mode switching

The Q series C24 requires approximately 400 ms as processing time of mode switching only.

While the mode switching is being executed, the setting values cannot be stored into the buffer memory special

applications area and data cannot be transmitted between the Q series C24 and the external device.

(4) Linked operation mode switching

Do not switch the mode when two interfaces of the Q series C24 are in linked operation. Also, do not switch the

mode for linked operation.

Mode switching signal

X6/XD

Mode switching

processing

Approx. 400 ms