Оценок - 4, средний балл: 4.3
(
)
)
|
К этому устройству также есть другие инструкции:
Фрагмент инструкции
It sends out an exclusive message completely independent for all exclusive messages (type IV) : of a receiving device status. Byte Description FOH Exclusive status 41 H Manufacturer ID (Roland) DEV Device ID MDL Mode! ID CMD Command ID [BODY] Main data F7H End of exclusive # MIDI status ; FOH, F7H An exclusive message must be flanked by a pair of status codes, starting with a Manufacturer.....ID immediately after FOH (MIDI versionl.O). # Manufacturer- # Device- tD : # Model- ID : ID : 41 H The Manufacturer-ID identifies the manufacturer of a MIDI instrument that triggeres an exclusive message. Value AIH represents Roland’s Manufacturer-ID, DEV The Device-ID contains a unique value that identifies the individual device in the multiple implementation of MIDI instruments. It is usually set to ООН - OFIi, a value smaller by one than that of □ baste channel, but value 00ii - IF!I may be used for a device with multiple basic channels. MDL The Mode!-ID contains a value that uniquely identifies one model from another. Different models, however, may share an identical Model-ID if they handle similar data. The Model-ID format may contain ООН in one or more places to provide an extended data field. The following are examples of valid Mode!-IDs, each representing a unique model : 01H 02H 03H ООН, 01H ООН, 02H ООН, ООН, 01 н # Command- ID CMD The Command-!D indicates the function of an exclusive message. The Command-ID format may contain 0011 in one or more places to provide an extended data field. The following are examples of valid Command - IDs . each representing a unique function : Connection Diagram Device (A) Device (8) Connections point2 is essential for "Request data" procedures (See Section!!.) # Handshake- transfer procedure (See Section4 for details.) This procedure initiates a predetermined transfer sequence (handshaking) across the interface before data transfer take; place. Handshaking ensures that reliability and transfer specs are high enough to handle a large amount of data. Connection Diagram Device (A) Device (B) Connectionat pointsl and 2 is essential. Notes on the above two procedures *There are separate Command-IDs for different transfe procedures. *DevicesA and B cannot exchange data unless they use th1 same transfer procedure, share identical Device-ID and Mode ID, and are ready for communication. □ One - way Transfer Procedure j This procedure sends out data all the way until it slops whe the messages are so short (hat answerbacks need not b checked. For long messages, however, the receiving device must acquir each message in time with the transfer sequence, which insert intervals of at least 20milliseconds in between. Types of Messages Message Command ID Request data t RQt 01H) Data set ! DTI (12H) 01H 02H 03H 00H, 01H ООН, 02H ООН, ООН, 01 н # Main data : BODY This field contains a message to be exchanged across an interface. The exact data size and contents will vary with the Model-ID and Command-Ш. Ш Address- mapped Data Transfer j Address mapping is a technique Sur transferring messages conforming to the data format given in Section I. ¡1 assigns a series of memory-resident records— waveform and tone data, switch status, and parameters, lor 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. # Request data # 1 : RQ1 <11H; This message is sent out when there is a need (o acquire dal from a device at the other end of the interface. It contains dal for the address and size that specify designation and iengtl respectively, of data required. On receiving an RQ1 message, the remote device checks i memory for the data address and size that satisfy the requc: If it finds them and is ready for communication, the device w transmit a "Data set ! (DTI)" message, which contains II requested data. Otherwise, the device will send out nothing. Byte Description FOH Exclusive status 41 H Manufacturer ID (Roiand) DEV Device ID MDL Model ID 1 1 H Command ID aaH Address MSS LS8 s^H Size MSB lsb sum Check sum F7H End ot exclusive *The size of ¡he requested data does no! indicate ¡he number of bytes that will make up a DTI message, but represents the address fields where ¡.he requested data resides. *Some models are subject id limitations in data format used for a single transaction. Requested data, for example, may have a limit in length or musl 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 least significant 7 bits are zero ...