Epson ActionLaser 1600, Service Manual

Page: 31 / 181

Printer Features
RD+, RD:
Serial ASCll data input from the computer.
HIGH level: when RD+ voltage is higher than RD voltage.
LOW level: when RD+ voltage is less than RD voltage.
Logic 0 is SPACE and logic 1 is MARK; MARK state must be maintained between
transmitted character codes.
H a n d s h a k i n g
When the vacant area for data in the input buffer drops to 256 bytes, the printer
outputs an X-OFF code or sets the DTR signal level to LOW, indicating that the
printer cannot receive more data. Once the vacant area for data in the buffer
recovers to 512 bytes, the printer outputs an X-ON code or sets the DTR flag to
HIGH, indicating that printer is again ready to receive data.
Protocols
There are three types of protocols, as listed below, and each of them can be
designated by SelecType independently.
DTR/DSR protocol
SelecType is used to execute the DTR/DSR control protocol. The DTR signal is set
to HIGH when the printer is ready to receive data, and to LOW when conditions
indicate an error or that the receiving buffer is full.
When the error is cleared and the printer returns on line, the signal returns to
HIGH. When SelecType is used to set the DTR control OFF, DTR is always set
HIGH. The printer transmits TXD only when DSR is at the HIGH level (DSR is
always considered HIGH when the SelecType setting for DSR is OFF).
X-ON/X-OFF transmission is independent from the DSR state.
X-ON/X-OFF (DC1/DC3) protocol
SelecType is used to execute X-ON/X-OFF protocol. The X-OFF (DC3) code is
output if status indicates an error, and the printer warns the host to stop data
transmission within 128 characters. No further X-OFF codes are sent in response
to additional data received from the host after the X-OFF code has been sent once.
The X-ON (DC1) code is output after all conditions given in error are cleared.
When the remaining capacity of the receive buffer reaches 256 characters, X-OFF
(DC3) is output once. It is sent only once, even if there are multiple errors. The
printer goes on line automatically at power on, and outputs an X-ON code.
Transmission of X-ON/X-OFF codes can be defined by SelecType.
O p t i o n a l L o c a l T a l k I n t e r f a c e
This printer can use the optional LocalTalk interface module.
Type:
LocalTalk
Signal level: Same as RS-422 signal level
EPSON ActionLaser 1600 Service Manual
1-27