APPENDIX

Appendix 2.3.2 Installing the Q series C24 into existing systems

MELSEC-Q

This section shows the notes when installing the Q series C24 into an existing system that uses UC24/C24-S8.

(1) Data communication using m:n connection

When the Q series C24 is installed into an existing system that has an m:n system structure between the PLC CPU and external devices, and data communication is performed using the MC protocol, the following notes should be considered:

(a)Accessing the PLC using a frame for form 5

When the UC24/C24-S8 is connected on the line, it is not possible to access the PLC in the QnA compatible 4C frame (form 5) for binary code communication.

(b)Data communication between external devices

1)When data communication is performed in order to link with an external devices to perform a 1:1 communication with the PLC CPU, it is necessary to change the station number (80H to A0H 00H to 1FH) designated in the "Station number" and "Local station number" items in the messages on the external device side. (It is not necessary to specify this when an A compatible 1C frame is used.)

Alternatively, it is necessary to change the message frame so that it has a data order different from that of the MC protocol.

•Station number: Designate the number of device to which data is sent

•Local station number: Designate the number of the device that sends data

2)Perform the data communication according to Chapter 14 of the User's Manual (Application).

(c)Processing reception data on the external device side

Set the external device so that it ignores the following reception messages that are unrelated to the local station.

• The command message and the corresponding response message that are sent from other stations when accessing the PLC CPU using the MC protocol.

• Messages when accessing between external devices.

(2)Data communication using 1:n connection

When the UC24/C24-S8 is connected on the line, it is not possible to access the PLC in the QnA compatible 4C frame (format 5) for binary code communication.

POINT

Since performances and response speeds are different between the Q series C24 and the UC24/C24-S8, communication may not be performed normally when a PLC module in the A series is replaced by a Q series PLC.

When a module is changed to a Q series PLC module, make sure to check operation.

App. - 13

App. - 13