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К этому устройству также есть другие инструкции:
Фрагмент инструкции
The exact data size and content will vary with the Model ID and Command ID. 2. Address-mapped Data Transfer Address mapping is a technique for transferring messages conforming to the data format given in Section 1. It assigns a series of memory-resident records–waveform and tone data, switch status, and parameters, for example, to specific locations in a machine-dependent address space, thereby allowing access to data residing at the address a message specifies. Address-mapped data transfer is therefore independent of models and data categories. This technique allows use of two different transfer procedures: one- way transfer and handshake transfer. One-way transfer procedure (See Section 3 for details.) This procedure is suited to the transfer of a small amount of data. It sends out an Exclusive message completely independent of the receiving device’s status. Device (B) MIDI IN MIDI OUT Device (A) MIDI OUT MIDI IN 1 2 Connection at point 2 is essential for “Request data” procedures. (See Section 3.) MIDI Implementation Handshake-transfer procedure (This device does not use this procedure) This procedure initiates a predetermined transfer sequence (handshaking) across the interface before data transfer takes place. Handshaking ensures that reliability and transfer speed are high enough to handle a large amount of data. Device (B) MIDI IN MIDI OUT Device (A) MIDI OUT MIDI IN 1 2 Connection at points 1 and 2 is essential. Notes on the above procedures • There are separate Command IDs for different transfer procedures. • Devices A and B cannot exchange data unless they use the same transfer procedure, share identical Device ID and Model ID, and are ready for communication. 3. One-way Transfer Procedure This procedure sends out data until it has all been sent and is used when the messages are so short that answerbacks need not be checked. For longer messages, however, the receiving device must acquire each message in time with the transfer sequence, which inserts 20 milliseconds intervals. In this method, as for the receiving device, it is necessary to receive data correctly in time. Types of Messages Message Command ID Request data 1 RQ1 (11H) Data set 1 DT1 (12H) Request data 1: RQ1 (11H) This message is sent out when there is a need to acquire data from a device at the other end of the interface. It contains data for the address and size that specify designation and length, respectively, of data required. On receiving an RQ1 message, the remote device checks its memory for the data address and size that satisfy the request. If it finds them and is ready for communication, the device will transmit a “Data set 1 (DT1)” message, which contains the requested data. Otherwise, the device won’t send out anything. Byte Description F0H System Exclusive Status 41H Manufacturer ID (Roland) DEV Device ID MDL Model ID 11H Command ID aaH Address MSB : : : : Address LSB ssH Size MSB : : : : Size LSB sum Check sum F7H EOX (End of System Exclusive) • The size of the requested data does not indicate the number of bytes that will make up a DT1 message, but represents the address fields where the requested data resides. • Some models are subject to limitations in data format used for a single transaction. Requested data, for example, may have a limit in length or must be divided into predetermined address fields before it is exchanged across the interface. • The same number of bytes comprises address and size data, which, however, vary with the Model ID. • The error-checking process uses a checksum that provides a bit pattern where the last 7 bits are zero when values for an address, size, and that checksum are summed. MIDI Implementation Data set 1: DT1 (12H) This message corresponds to the actual data transfer process. Because every byte in the data is assigned a unique address, a DT1 message can convey the starting address of one or more bits of data as well as a series of data formatted in an address-dependent order. The MIDI standards inhibit non real-time messages from interrupting an Exclusive one. This fact is inconvenient for devices that support a “soft-thru” function. To maintain compatibility with such devices, Roland has limited the DT1 to 256 bytes so that an excessively long message is sent out in separate ‘segments.’ Byte Description F0H System Exclusive Status 41H Manufacturer ID (Roland) DEV Device ID MDL Model ID 12H Command ID aaH Address MSB : : : : Address LSB ddH Data MSB : : : : Data LSB sum Check sum F7H EOX (End of System Exclusive) •A DT1 message is capable of providing only the valid data among those specified by an RQ1 message. • Some models are subject to limitations in data format used for a single transaction. Requested data, or example, may have a limit in length or must be divided into predetermined address fields before it is exchanged across the interface. • The number of bytes comprising address data varies from one Model ID to another. • The error-checking process uses a checksum that provi...