Epson FX-1180 - Impact Printer, Service Manual

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Product Description
EPSON FX-880/FX-1180 Service Manual 1-19
Interface Selection
The printer selects the interface automatically, unless the user manually overrides it.
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Manual selection
The user can override automatic selection by selecting either the built-in parallel or the optional Type-B
interface in the default setting mode. (See “Control Panel Operation” later in this chapter.)
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Automatic selection
Normally, interface selection is automatic. (This is the factory-set default, but it can be changed in the
default settings.) With automatic selection enabled, the printer initializes to the idle state and scans its
interfaces. When the printer receives data, the interface that receives the data first is selected. As long
as the host continues sending data or the printer interface is busy, the selected interface remains active.
When the host stops transferring data and the printer sits in standby for the number of seconds specified
in the default settings, the printer returns to the idle state and the interface is de-activated.
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Interface state and interface selection
When the printer is initialized or returns to the idle state after printing, three things happen:
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The parallel interface goes into the ready state.
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If an optional interface card is installed, the printer sends it an enable command.
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If a serial interface card is installed, it sends an XON code and sets the DTR signal to SPACE.
When an interface is not selected, various things can happen:
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When the parallel interface is not selected, it goes into a busy state.
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When an optional interface card is installed and not selected, the printer sends a disable
command to the optional interface.
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When the Type-B serial interface card is installed and it is not selected, the interface sends an
XOFF code and sets the DTR signal to MARK.
Interrupt signals, such as the INIT signal for the parallel interface, are not effective unless the interface to
which it is directed is selected.
Preventing Data Transfer Timeout in the Host
Generally, a host abandons data transfer to a peripheral when the peripheral is in the busy state for a
period of 30 seconds or more, depending on the default settings of the host. To prevent time-out in the
host, the printer begins receiving data more slowly after the input buffer has received several hundred
bytes of data. Data transfer may then slow to as little as a few bytes per minute, with the printer
registering a busy state only if the input buffer fills completely.