1. If the host computer is not equipped with a power
supply for the Current loop interface, these
jumpers must be connected to perform communica-
tion via the Current loop interface
2 Either J8 or j9 jumper is connected at the factory,
and you should not change this setting
3. Either JCX or JCF jumper must be connected.
4.
Either JCL or JRS jumper must be connected.
Jumper settings for RS-232C and current loop
Refer to the table below for information on the four
available handshaking protocol selections.
Table 7. Protocol selection in RS-232C mode
Table 8.
Protocol selection in Current Loop mode
I JCL OFF
12
Protocol
protocol is a system in which the printer
transmits a code to the computer to indicate that it
cannot accept more data, and a second code when it is
once again ready. This protocol can be performed under
either RS232C or 20 mA Current Loop signal levels.
The C82302*/C82304* interface board sends an X-on
<11>
H
code
when it is ready to receive data, and an X-
off
<13>H
when
it is busy. The X-On/X-off
Signals
may
be transmitted from the TXD
at
Handshaking p r o t o c o l
Note
X-on/X-off protocol cannot be performed when the
buffer
operation
is disabled. But the DTR flag protocol
is still possible.
After the X-on flag has been set, data can be accepted up
to the maximum capacity of the buffer.
l
Transmit timing of X-off signal
The X-off signal is transmitted when the vacant area
for bytes in the buffer drops to 512 or 16 bytes
(selectable with DIP switch 2-6).
l
Data can be sent to the printer even after the X-Off
signal is transmitted as long as sufficient room for
data remains in the buffer.
However,
if the transmit-
ted data exceeds the vacant area in the buffer, it will
be discarded. X-off character will be transmitted
again when the remaining buffer capacity is actually
0 bytes. At the same time, BS code
<08>H
and “/”
character
<2F> H
will be sent to the printer.
14
serial data communications
The C82302*/C82304 interface allows you to select
either RS-232C or 20 mA Current Loop signal leve
data communication but never both at the same time
This interface board also provides for either DTR (Data
Terminal Ready) or X-on/X-off handshaking protocol.
About data entry
To accommodate data entry, the C82302*/C82304*
interface board is equipped with a buffer that temporar-
ily stores data before transferring it to the printer When
this buffer becomes full, any additional transmitted data
cannot be accepted and is discarded.
To prevent such
data loss, special handshaking protocols are provided
regulate the flow of data transmissioh
13
l
greater than the preset value of the buffer recovery
timing. Refer to Table 5. for buffer recovery timing
information
Figure 3. X-on/x-off timing
DTR protocol
This interface board also provides for DTR handshaking
protocol using either RS-232C or Current Loop signal
levels
Under this system, when the printer is turned on the
DTR enters the SPACE state, meaning that data entry is
enabled. When the rate of data reception is greater than
that of printing, the buffer gradually fills up. once the
vacant area for transmitted bytes drops to 512 or 1
bytes, the DTR sets the status flag to prohibit further.
data entry. This flag is output through the DTR (pin No.
20) under RS-232C signal levels, and through the TTY-
TXD (pin No. 17) under Current Loop levels.
15
