Prevention Hosts From Data Transfer Time-Out; Interface Selection - Epson DLQ-3000 Service Manual

DLQ-3000+

1.4.5 Prevention Hosts from Data Transfer Time-out

Generally, hosts abandon data transfer to peripherals when a peripheral is BUSY
continuously for dozens of seconds. To prevent this kind of time-out, the printer receives
data very slowly, several bytes par minute, even the printer is in a busy state. This
slowdown starts when the remainder of input buffer drops under several hundreds of bytes.
Finally, the printer is BUSY continuously when the input buffer is full.

1.4.6 Interface Selection

The EPSON DLQ-3000+ has three types of interfaces: Parallel, Serial, and optional Type-B.
Each interface can be selected manually by SelecType or automatically. Both modes are
selected thorough the default setting mode.
Y
Manual selection
One of the 3 interfaces can be selected by SelecType.
Y
Automatic selection mode (Enabled by SelecType)
When the printer is powered on, the printer is initialized to the idle state scanning which
interface receives data. Then the interface that receives data first is selected. When the
host stops data transfer and the printer is in stand-by state for the seconds specified by
SelecType, the printer is returned to the idle state. As long as the host sends data or the
printer interface is busy state, the selected interface is left as it is.
Interface selection and interface state
Interface selection and the corresponding interface states are as follows:
Y
When an interface other than parallel interface is selected, the interface goes into
the BUSY state.
Y
When an interface other than serial interface is selected, the interface sends XOFF
and sets the DTR signal MARK.
Y
When an interface other than optional interface is selected, the printer sets
"OFFLINE" bit of MNSTS register to the optional interface.
Y
When the printer is initialized and returned to the idle state:
The parallel interface goes into ready state.
The serial interface sends XON and sets the DTR SPACE and the printer
resets OFFLINE bit of MNSTS register to the optional interface.
Note: An interrupt signal such as /INIT signal on the parallel interface is not effective while
that interface is not selected.
1-36
Figure 1-15. Interface Selection
Rev. A