The Mitsubishi Bidirectional protocol is one of the serial RS-232 and RS-485 protocols supported by the RMC75S. The Mitsubishi Bidirectional protocol is for use with Mitsubishi's Q-series QJ71C24N serial communication module. This protocol requires RMC75 firmware version 1.60 or newer and RMCTools version 1.60.0 or newer.
The QJ71C24N supports several communication protocols. The one that matches the needs of the RMC75S is the Bidirectional protocol. It allows the Q-series PLC to read and write binary data from an RMC75S over serial RS-232 or RS-485. The RMC75S requires that the data sent via the Bidirectional protocol be formatted as described in this topic.
The Bidirectional protocol is described in Mitsubishi’s “Q Corresponding Serial Communication Module User’s Manual (Basic)”. The manual part number is SH (NA)-080006-J. Search for 080006 on www.meau.com in the Downloads>>Manuals section.
A sample program for using the Bidirectional protocol is available on the downloads page of Delta's website at https://deltamotion.com/dloads. This should be used as a starting point for any Mitsubishi Q-series program using the QJ71C24N module and an RMC75S.
Configuring
The instructions below are with GX Developer version 8.25B.
Switch Settings
Set the intelligent function module switches for the desired serial settings. See section 4.5.2 of the following Mitsubishi manual: Q Corresponding Serial Communication Module (User’s Manual).
The data bits must be 8 and the protocol must be Bidirectional. Make sure you set the baud rate, parity and stop bits identically in the QJ71C24N and RMC75S.
Writing to the RMC75S
Use the GP.BIDOUT instruction to write to registers in the RMC75S. It is described in section 9.5 of the “Q Corresponding Serial Communication Module User’s Manual (Basic)”. The RMC75S requires that the data sent to it via this instruction is in the format shown below.
|
0
(16 bits integer) |
Register File (16 bits integer) |
Register Element (16 bits integer) |
Data Item 1 (32 bits, typically floating-point) |
Data Item 2 (32 bits, typically floating-point) |
… |
Data Item n (32 bits, typically floating-point) |
Description:
|
0 |
This 16-bit word must be 0. |
|
Register File |
This 16-bit word is the file number of the register’s address in IEC format. For example, for %MD8.12, the file number is 8. |
|
Register Element |
This 16-bit word is the element number of the register’s address in IEC format. For example, for %MD8.12, the element number is 12. |
|
Data Time 1 |
The RMC75 has 32-bit registers. Therefore, you can only write 32-bit words. Most RMC75 registers are floating-point; a few are integers. |
|
Data Item n |
To write n 32-bit registers to the RMC75, make sure the TxCount is correct. It should be (2 x n) + 3. |
Example
A programmer wishes to write 5 values to the variable table (address %MD56.0). These values are: 32.876, 1.0, 12.0, 5.432, 862.0.
The send data for the GP.BIDOUT instruction would be as follows:
|
0 (16 bits) |
56 (16 bits) |
0 (16 bits) |
32.876 (32 bits) |
1.0 (32 bits) |
12.0 (32 bits) |
5.432 (32 bits) |
862.0 (32 bits) |
Reading from the RMC75S
To read registers from the RMC75S, use the GP.BIDOUT instruction to send a read request and then use the GP.BIDIN instruction to read the received data. The GP.BIDIN instruction is described in section 9.6 of the “Q Corresponding Serial Communication Module User’s Manual (Basic)”.
Writing the Read Request
To send a request a read from the RMC75S, the send data of the GP.BIDOUT instruction must be formatted as shown below. Each box is a 16-bit word.
|
Read Count (16 bits) |
Register File (16 bits) |
Register Element (16 bits) |
Description:
|
Read Count |
This is the number of 32-bit registers to be read from the RMC75, starting at the address given by the file and element. |
|
Register File |
This is the file number of the address of the first register to be read. For example, for %MD8.12, the file number is 8. |
|
Register Element |
This is the element number of the address of the first register to be read. For example, for %MD8.12, the element number is 12. |
Receiving the Returned Data
After the write request is sent, the RMC75S will return the requested data. The QJ71C24N X3 input indicates whether data has been received. To read the receive buffer, use the GP.BIDIN instruction. The returned data is in the format shown below:
|
Count
(16 bits) |
Data Item 1
(32 bits) |
Data Item 2
(32 bits) |
… |
Data Item n
(32 bits) |
Description:
|
Count |
This is the number of 32-bit words read from the buffer. |
|
Data Item 1-n |
This is the returned data. |
See Also
Communications Overview | Using the Mitsubishi Q-Series PLC with the RMC
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