a ! i ■ i i -11 ■■ ACK (--Í::■!"!) End ot data EGO i'TaM) Cotraraaiaieaorna re i or C'fifi fâ'EI'O fie tec don iAJC S ; i ! ; .# Want to send data : WSD c40H) This message is s message, (be rentóle dcvic« chccfcs ¡is meniory for ihe sfieciiicsj .¡ara address and size which v/il! satisfy the reciñes!.. If it. finds them and is ready for coiaiiminicaiion , the device will return an ’'Acknowledge: (ACK)" r i o .i y i1 Od'ssry'iiy.y it v.'ill retorts a "i'ítyiec I ion - syl- S' messa/ie. 8 y t e /.aesca ; ■' :. i: i FOH !:. y si-a si ve -a, -a - ; 4 1 id Ivíanufactijces if) (Roland) DkV Device ID Mijk. Sa ■ i •1 ifa AÜH (AatriaiaraJ if) Aiidr teas iVlSIB LSB said Si-e ‘sTàlà LSB 51; ill Check Siam F7I ' ¡and of exclusive 9 Device R requesling data from Dovice A i s-v h s- I i seal cf s an I. "Í rn e s sa g e t. o I >e vice A. (.'h ec !■; i n K lise message. Device A rxasds a 1)1 I message hack to Dev tee D. ♦ The size of the dafa to be sent does not indicaie (he number of bytes ibai make up a "Data set (DAT)" message, but represents the address fields where the data should reside. ♦ Some models are subject to limitations in data formal osed for a single irarisaciion, ReQuested data, for example, may have a hunt til length or nnts! be divided into predetermined address fields before it is exchanged across ihe interface. » d'he sani" nimih's- nf :;y:e; : o-eprisi>s address and si/e data, which, hie.wwi i , \ ai y wilh llw Voiid ID. *The era ■: ■ l‘n ■■ k ine -inii a, i;..e, a cheeksom ihal provides a hii [xn.icai v, 11--I i die :■ a■.'! '.igiiiI icard 7 bits are zero when values loi an sddiess, siae, ano that cnecksnrn are sunttned. Request data: RQD (41H) This message is sent out when ihere is a need In acquire dsla from a device ;.u the oilier end of (he interface. ]! contains dala for (he address and size dial specify designalion and length, respectrvely, of data required. On receiving an KQD message, tin ren;r.|e device checks i!s memory for the data address and size which satisfy the revues!, li il finds (hens and ¡s ready for communication, the device will transmit a "Data set (OAT)" message, which contains (lie requested data. Otherwise, it will return a "Rejection (RJC)’’ message. Byte С с so rip iioo 1- OH Exclusive Si.SP.:s A 1 H M a ci i j г a e li] r e s ! D (Hoi a п ;:0 DEV iJevice ID VI DC Model ID A ) 1-1 . Command ID a a FI Address MSB L.SR sum L.SB Clioc 1: surn F7H Is rid of e lies ive *The size of (lie requested data does not indicate the number of bytes, ‘fiat maScc up a "Data set (DAT)" message, but represents the address fields where the requested dala resides. * Some models are subject to ¡imitations in data format used for a single transaction, Requested data, for example, may have a limit in length or mnsl I)c divided into pct’determined address /ieids before j! rs exchanged across the interface. *Tlie same number of bytes comprises address and size data, which, however, vary with the iVkxiel ■ ID. *The error checking process uses a checksum that provides a bit pattern where the least significant 7 bits are zero when vaiues for an address, size, and that checksum are summed. Data set : DAT (42H) This message corresponds io !he actual data transfer process. Because every byte in lilt: data is assigned a unique address, the message can convey the shirting address of one or more data as well as a series oi' data formatted in an address dependent order. All hough I he MIDI standards inbihit non -real lime messages from interrupting an exclusive one, some devices support a soft through " mechanism for such interrupts . To maintain!:ompaiibilily with such devices, Roland has limited the DAT !o 1’56bytes so (hat an excessively long message- is sent out in separate segments. *A DAT message is capable of providing only the valid data among those specified by an RQD or '.VSH message. ¡t’Some models are subject to limilat'ons in data foimat osed for a single transaction. Requested dala, foi example. mav have a limit in length or must tx- divided nun nre«iet'*nnsncil address fields before it Is exchanged across the interface. ^The number of bytes comprising address data vanes from one model ID to another. *The error checking process tises a checksum that provides a bit pattern where (he leas! siKtiificanl 7 inis are zero when values for an address, size, and that check sum are summed. * Acknowledge : ACK (43H) This message is sent out when no error was delected on reception of a WSD, DAT, "l-'nd of dala (ROD)", or some other message and a requested setup or ad ion is complete. Unless it receives art ACK message, the device at die other end will not proceed to the next operation. Byte Description FORI Exclusive stal us ...
