Specifications
i50 Manual (5.10)
Page 13
© 2015 Datalink Systems, Inc.
www.datalinksystemsinc.com
4.5.3 COM2/COM3
COM2 and COM3 use male connectors, through which the i50 acts as DTE (data terminal
equipment). These ports are intended to connect to external modems, but may also be used for other
purposes.
COM2 provides most handshaking and control pins, allowing full control of external devices and
hardware flow control to prevent data loss. Table 4 shows the COM2 pin descriptions.
DB-9 Pin (male)
Pin Name
Direction (relative to i50)
1
DCD
Input
2
RX
Input
3
TX
Output
4
DTR
Output / VOUT*
5
GND
-
6
DSR
Input (ignored)
7
RTS
Output
8
CTS
Input
9
RI
Input
Table 4 – COM2 Connector
Note: the COM2 DSR pin is ignored by the CPU.
COM3 uses a three-wire interface, so is unable to support hardware handshaking. Table 5 shows the
COM3 pin descriptions.
DB-9 Pin (male)
Pin Name
Direction (relative to i50)
1
Not used
-
2
RX
Input
3
TX
Output
4
DTR
Output (always high) / VOUT*
5
GND
-
6
Not used
-
7
RTS
Output (always high)
8
Not used
-
9
VOUT
Factory Option
Table 5 – COM3 Connector
Note: the COM3 DTR and RTS pins are always active (high) when COM3 is awake. This allows
attached devices to communicate if they are expecting these signals to be present.
COM3 pin 9 can be modified at the factory to provide a VOUT source. See section 4.2 for more
information.
* In i50 hardware version 3, the COM2 and COM3 DTR lines are connected internally to the VOUT
signal.