7 DATA COMMUNICATIONS USING BIDIRECTIONAL PROTOCOL

MELSEC-Q

POINT

(1)The position and size of the receive area in the buffer memory can be changed with GX Configurator-SC in accordance with the specifications of the external device and the received data length. (See Sections 8.4.5 and 8.4.7.)

(a)When changing the position and size of the receive area in the buffer memory with GX Configurator-SC, specify as follows:

1)Receive buffer memory head address designation

Designate the starting address for the area to be used as the receive area in the user definable area of the buffer memory (address: 400H to 1AFFH, 2600H to 3FFFH).

2)Receive buffer memory length designation

Designate by addresses the length of the area (0001H to 1A00H) to be used as the receive area in the user definable area of the buffer memory (address: 400H to 1AFFH, 2600H to 3FFFH).

(b)If the following functions are also used when the position and size of the receive area in the buffer memory are changed, make sure that the addresses of the receive area do not overlap with those for the buffer memory that stores the transmission and reception data to be used by these functions.

1)MC protocol buffer memory read/write function

2)MC protocol on-demand function

3)Non procedure protocol transmission/receive function

4)Bidirectional protocol transmission/receive function

5)Communication data monitoring function

(2)When sending data to the Q series C24 from the external device, one of the following two adjustments should be made so that the relationship shown below is maintained.

1) Reduce the send data size.

2) Increase the receive area.

(Receive data storage area) ≥ (Size of data portion sent from the external device)

7 - 5

7 - 5