2.7 Communications with a Mitsubishi PLC (QnA-compatible 3E Frame Protocol)
Message Functions
2-169
Ethernet Communications
Data Size (PARAM17)
Set the data size for the read/write request as the number of bits or words.
Be sure that the last data address that is determined by the offset, data address, and data size does not
exceed the valid data address range.
The range that is allowed for the data size depends on the function code and data area.
*1. In the loopback test, the message sends two words (4 bytes) of data that must be returned.
*2. When using TCP communications, the upper limit is restricted by the MTU size. When communicating with TCP, the
maximum size is the size of data that can be sent in a single segment.
Remote CPU Module Number (PARAM18)
This parameter is not used for the QnA-compatible 3E Frame protocol.
Reserved for System (PARAM19)
This parameter is used by the system.
Local Station Data Address (PARAM20 and PARAM21)
Set the address of the read data destination or write data source in the MP3000-series Controller.
The address is set as the word offset from address 0.
QnA-compatible 3E
Frame Commands
MEMOBUS
Command
Function
Points
Command
Subcom-
mand
0401 hex
0001 hex
01 or 02 hex
Reads bit devices in units of one point.
1 to 2,000 points
0000 hex
03 hex/04 hex
Reads word devices in units of one point.
1 to 125 points
09 or 0A hex
1 to 960 points
∗
2
1401 hex
0001 hex
05 hex
Writes bit devices in units of one point.
1 point
0F hex
1 to 800 points
0000 hex
06 hex
Writes word devices in units of one
point.
1 point
0B hex
1 to 960 points
∗
2
10 hex
1 to 100 points
1402 hex
0000 hex
0E hex
Writes word devices in units of one
point.
1 to 160 points
0403 hex
0000 hex
0D hex
Reads word devices in units of one point.
1 to 192 points
0619 hex
0000 hex
08 hex
Performs a loopback test
*1
(word data
loop)
∗
1
2 points
Do not change the value of PARAM19 from a user program or by any other means.
Note
