Three Epson serial interfaces are suitable for LQ printers. All three

offer a choice of 7-bit or g-bit data, and support Current Loop operation in addition to RS-232C. They also offer a choice of other features, which are listed in Table F-2.

Table F-2. Send interface

 

#a143

#al45

#al48

 

X-on/X-off control

yes

no

yes

 

Self test

no

loopback

loopbackl

 

 

 

 

line monitor

 

Built-In data buffer

none

2K

218K

 

X-on/X-off 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 more ready

The loopback self-test mode allows direct testing of the functions of the interface without connecting a computer; line monitor mode is rather like the LQ data dump mode.

Identifying a serial interface board

All Epson interfaces have the EPSON name printed on them. If the board has an identification code printed on it, it will be a four digit number beginning with an eight. The number should be one of the numbers in Table F-3.

If the board has no identification code, or if you are unsure whether the number you have located is the correct code, check the number of DIP switches on the board against Table F-3.

Table F-3. Number of DIP switches

Choosing and Setting Up Optional Interfaces

F - 3