O 2.3 Parameter Set Transfer Modes; Communication Modes; One-Way Mode Communication Flow; Handshake Mode Communication Flow - Casio CTK-671 Midi Implementation Manual

CTK-671 MIDI Implementation
Receiving Device Sending Device
----------------------- ---------------------
IPR
IPC
See "Parameter List" in this document for information about which parameters can
actually be sent.
2.3 Parameter Set Transfer Modes

2.3.1 Communication Modes

Parameter Sets can be transferred by bulk dump, using the types of message exchanges
described below.
• One-way mode Parameter Set send/receive
• One-way mode Parameter Set send request send/receive
• Handshake mode Parameter Set send/receive
• Handshake mode Parameter Set send request, receive rejected, error notification send/
receive
With the One-way mode, the sending device sends data and ends the session without
paying any attention to the response of the receiving device. This mode is best for one-
way transfers from a sequencer or similar device.
With the Handshake mode, after the sending device sends the data, it confirms response
from the receiving device and then advances to the next session. This is a high-speed
mode in which there is no time wasted waiting.
See "Parameter Set" in this document for information about how Parameter Sets are
actually allocated.
In order to ensure maximum speed for bulk dumping of a Parameter Set, the data format
used is different from that used for Individual Parameter Change. Data is transferred as-
is, using the CTK-671 memory image.
One Parameter Set can be transferred per session.
A large Parameter Set can be divided into multiple packets for transfer. In this case,
<index> field packet numbers are used.
When transferring multiple groups of small Parameter Sets, each Parameter Set must be
allocated to its own packet. Multiple Parameter Sets cannot be included within the same
packet.

2.3.2 One-way Mode Communication Flow

A session starts with the receiving device sending a request using a BDR, or with the
sending device sending BDS data. The session ends after transfer of all of the data in
the Parameter Set being transferred by the sending device is complete.
When the CTK-671 receives a BDR, it sends back the applicable Set as a BDS. When
the CTK-671 receives a BDS, it changes the corresponding Parameter Set value.
Data is divided into multiple packets of 256 bytes or less each, and transfers them at
fixed intervals (20 msec).
A final EOD informs the receiving device that the session is ended.
Receiving Device Sending Device
----------------------- ---------------------
BDR
BDS
20 msec or greater interval
BDS
20 msec or greater interval
BDS
20 msec or greater interval
:
:
EOD
Operation
---------------------------------------
Send Request (Optional)
Data Transfer
Operation
------------------------------
Send Request (Optional)
Data Transfer
Data Transfer
Data Transfer
Data Transfer

2.3.3 Handshake Mode Communication Flow

A session starts with the receiving device sending a request using an HDR, or with the
sending device sending HDS data.
The sending device does not send the next packet until it receives an ACK from the
receiving device. The maximum wait time is at least 100 msec. Failure of a response to
arrive within the wait time (at least 100 msec) is treated as a timeout error, and data
communication is terminated.
The sending device resends the last data if the receiving device returns an HDE (error)
due to checksum mismatch, incompatible data structure, or some other reason. If an
error repeats a number of times (undefined), either the sending device or the receiving
device sends an HDJ to terminate the session.
A session ends after the sending device sends all the Parameter Sets, and sends a final
EOD in response to an HAD (ACK) from the sending device.
Receiving Device Sending Device
----------------------- ---------------------
HDR
HDS
HDA
HDS
HDA
:
:
HDA Acknowledge
EOD
The same packet is resent when a checksum mismatch or incompatible data structure
error is detected.
Receiving Device Sending Device
----------------------- ---------------------
HDR
HDS
HDA
HDS
HDE
HDS
:
:
HDE
EOD
Data send is canceled when ACK is not received.
Receiving Device Sending Device
----------------------- ---------------------
HDR
HDS
HDA
HDS
HDJ
(Send Canceled)
The session can be canceled for any reason by sending an HDJ. The HDJ can be sent
by the sending device or the receiving device. The bulk dump session is terminated
immediately upon receipt of an HDJ.
Receiving Device Sending Device
----------------------- ---------------------
HDR
HDS
HDA
HDS
:
HDJ
(Send Canceled)
10
Operation
-----------------------------
Send Request (Optional)
Data Send
Acknowledge
Data Send
Acknowledge
End Of Data
Operation
-----------------------------
Send Request (Optional)
Data Send
Acknowledge
Data Send
Acknowledge
Data Re-send
Acknowledge
End Of Data
Operation
-----------------------------
Send Request (Optional)
Data Send
Acknowledge
Data Send
Rejection
Operation
-----------------------------
Send Request (Optional)
Data Send
Acknowledge
Data Send
Data Receive Rejected