Owner`s manual

Page A-7Serial, Parallel, UPS and Ethernet Connector Configurations
RS-232 DB-9 to DB-25 Terminal Cables
This section tells you which pins to connect to construct cables for particular terminals
supported by Alpha Micro. We have grouped the signals into pairs which will also allow
longer and more reliable communication to the computer system.
The AM-60, AM-62, and AM-70 terminals are all RS-232 devices and use the same
cabling. The AM-62A, AM-65, AM-72, and AM-75 terminals when used as RS-232
devices, also use these pinouts.
The following table gives the pinouts required for RS-232 cables connecting a terminal
to the computer:
Pinouts for RS-232 Terminal-to-Computer Cables
Terminal End
DB-25 Connector
Computer End
DB-9 Connector
SIGNAL PIN# DIRECTION PIN# SIGNAL
TXD 2 -----> 2 RXD
GND 7 <----> 7 GND
RXD 3 <----- 3 TXD
DTR 20 -----> 4 CTS
The DTR connection (pin 20) to the computer (pin 4) can serve as ’READY/NOT BUSY’
handshake line to prevent ’overrunning’ the terminal with data. This protocol is also
effective for several printers used by Alpha Micro.
Caution: While this cable configuration enhances the use of the Alpha Micro terminals,
it may degrade system performance with other types of terminals and printers if they do
not provide a compatible DTR on pin 20. In such cases, the connection to pin 4 at the
computer end should be disconnected.
Eagle Series Computer Owner’s Manual, Rev. 03