Kawai MR210 Owner's Manual page 13

Before attempting to set the MIDI function, let's take a brief look at what MIDI is.
The letters MIDI stand for Musical Instrument Digital Interface, an international standard for connecting
synthesizers, drum machines, and other electronic instruments so that they can exchange performance
data.
instruments equipped with MIDI have three jacks for exchanging data: IN, OUT, and THRU. Each uses a
special cable with a DIN connector for connection (see p. 14)
IN: For receiving keyboard, timbre, and other data
OUT: For sending keyboard, timbre, and other data
THRU: For sending received data to another instrument without processing
Electrical and electronic musical instruments equipped with MIDI are able to transmit and receive perform-
ance data such as for keyboard and timbre.
Depending on the connection method, instruments are grouped as those which receive data (producing
sound according to data received from the connected instrument), those which send data (to the instru-
ments to which they are connected), and those which both send and receive data.
The cable is connected to the MIDI IN jack of the instrument receiving data and to the OUT jack of the
sending instrument. The THRU jack is used when the data received is to be sent to another instrument.
MIDI uses what are known as "channels" as a means of transmitting data for playing a specified instrument.
There are two types of channels, one for receiving and one for sending, and MIDI instruments are normally
equipped with both types. Receive channels are used when an instrument receives data from another
instrument, and send channels are used for transmission to another instrument.
For instance, let's say that three instruments are connected for playing in this way:
© © ®
Instrument @), which is sending, transmits the send channel along with keyboard and other data to instru-
ments © and @), which are receiving. This data is sent to instruments © and @), but the data will not be
received unless the receive channel for these two instruments matches the send channel used by instru-
ment ©.
There are 16 channels each (1 through 16) available for both sending and receiving.