Roland HP 2700 - Communication Error Message (ERR); Rejection Message (RJC)

Roland Exclusive Messages
z Request data: ROD (41H) + Acknowledge: ACK (43H)
ee
This message is sent out when there is a need to acquire data from
“a device at the other end of the interface. {1 contains data for the address
and size that specify designation and length, respectively, of data required.
On receiving an RQD message, the remote device checks its memory for
the data address and size which satisfy the request.
If it finds them and is ready for communication, the device will transmit
a “Data set (DAT)” message, which contains the requested data.
Otherwise, it will return a “Rejection (RJC)” message.
Exclusive status
Manufacturer ID (Roland)
Device iD
Modet ID
Command ID
Address MSB
LSB
Size MSB
LSB
Check sum
End of exclusive
* The size of the requested data does not indicate the number of bytes
that make up a “Data set (DAT)” 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 fength
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 least significant 7 bits are zero when values for an address,
size, and that checksum are summed.
x Data set: DAT (42H)
This message corresponds to the actual data transfer process.
Because every byte in the data is assigned a unique address, the message
can convey the starting address of one or more data as well as a series
of data formatted in an address-dependent order.
Although the MIDI standards inhibit non-real time messages from
interrupting an exclusive one, some devices support a “soft-through”
mechanism for such interrupts. To maintain compatibility with such
devices, Roland has limited the DAT to 256 bytes so that an excessively
long message is sent out in separate segments.
Exclusive status
Manufacturer ID (Roland)
Davice 1D
Mode! ID
Command !D
Address MSB
Data
‘
Check sum
End of exclusive
* A DAT message is capable of providing only the valid data among
those specified by an RQD or WSD message.
%* Some models are subject to limitations in data format used for a singic
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 number of bytes comprising address data varies from one model
ID to another,
%* The error checking process uses a checksum thal provides a bit patiern
where the feast significant 7 bits are zero when values for an address,
size, and that checksum are summed.
This message is sent oul when no error was detected on reception of
a WSD, DAT, “End of data (EOD)", or some other message and a
requested setup or action is complete. Unless it receives an ACK message,
the device at the other end will nol proceed {o the next operation.
Exclusive status
Manufacturer ID (Roland)
Device ID
Model 1D
Command ID
End of exclusive
#zEnd of data: EOD (45H)
This message is sent out to inform a remote device of the end of a
message. Communication, however, will not come to an end unless the
remote device returns an ACK message even though an EOD message
was transmitted.
Exclusive status
Manufacturer ID (Roland)
Device ID
Model ID
Command ID
End of exclusive
+ Communications error; ERR (4EH)
This message warns the remote device of a communications fault
encountered during message transmission due, for example, to a checksum
error. An ERR message may be replaced with a “Rejection (RJC)"
one, which terminates the current message transaction in midstream.
When it receives an ERR message, the sending device may cither attempt
to send out the fast message a second time or terminate communication
by sending out an RIC message.
Exclusive status
Manufacturer ID (Roland)
Device ID
Model iD
Command ID
End of exclusive
Rejection: RJC (4FH)
This message is sent oul when there is a need to lerminate communication
by overriding the current message. An RIC message will be triggered
when:
@ a WSD or RQD message has specified an iftegal data address or
size.
@ the device is not ready for communication.
@ an iMegal number of addresses or data has been detected.
@ data transfer has been terminated by an operator.
@ a communications error has occurred.
An ERR message may be sent out by a device on either side of the
interface. Communicalion must be terminated immediately when either
side triggers an ERR message.
Exclusive status
Manufacturer ID (Roland)
Device ID
Model ID
Command iD
End of exclusive