C.ITOH 8510A User Manual page 40

(12) Selection of data transmission speed (Unit: baud)
Speed 22-1 22-2 22-3
9600 Open Open Open
4800
Open
Open Closed
2400 Open Closed Open
1200 Open Closed
Closed
(ST)
600 Closed Open Open
300 Closed Open Closed
200 Closed Closed Open
110 Closed Closed Closed
Do not use current loop at more than 2400 BPS.
11-11. Data Protocol
This printer provides three types of transmission system.
(1) Data RDY /BSY system
This system uses the level signal (DTR) which indicates the printer state.
(2) EXT/ACK system (applicable to RD and CD)
This system uses the serial codes ASCII CODE-ETX, ACK.
(3) X ON/X OFF system (applicable to RD and CD)
This system uses the serial coded ASCII CODE-X ON, X OFF.
They are selected by using the dip switches.
This printer provides a data buffer which stores on the principle of "first-in, first-out". If the
host CPU continues to transfer data ignoring the signals from this printer, some data may be
lost.
(1) Data RDY /BSY system
When the remaining capacity of the data buffer becomes less than 30 bytes, the DTR signal
becomes low level. Therefore the printer outputs the BSY signal. When the remaining capacity
of the data buffer becomes more than 99 bytes, the DTR signal becomes high level and printer
becomes ready for receiving data.
The host CPU must stop the data transmIssion within 27 bytes after the DTR signal becomes low
level.
The host CPU transmits the data exceeding the capacity of the data buffer ignoring the BSY
signal, this printer receives the overflow data but it must be discarded.
At power on time, when the printer is ready to receive the data and is selected, the DTR signal
becomes ready state.
(2) ETX/ ACK system
When the buffer is ready to restore the data, it makes the DTR level high (ready state) and sends
out ACK code.
The printer stores the received data in the buffer, prints the data in series when it finds the ETX
code in the buffer.
When this performance is finished, the printer sends out the ACK code.
Therefore, the host CPU must transmit the next text when it receives the ACK code. And it is
necessary to include the ETX does properly in the data stream of the CPU considering the
capacity of the printer's buffer.
-38-