CallerID Whozz Calling? 4 POS Caller ID Technical manual - page 10
9
Appendix - RS232 Pin Outs
When the serial port is configured to “No Flow Control,” only Transmit and Ground connections are required. Pin
7 and Pin 8 need to be connected only if other serial flow control types are selected.
Computer DB9/M Serial Port
Monitoring Unit DB9/F
Pin
1
(Carrier
Detect)
Pin
1
(No
Connection)
Pin
2
(Receive
)
Pin
2
(Transmit)
Pin
3
(Transmit)
Pin
3
(Receive)
Pin 4 (Data Term. Ready)
Pin 4 (No Connection)
Pin
5
(Ground)
Pin
5
(Ground)
Pin 6 (Data Set Ready)
Pin 6 (Control Line between Units)
Pin 7 (Request to Send)
Pin 7
(Internal
Pin 8 (Clear to Send)
Pin 8
Connection)
Pin
9
(Ring
Indicator)
Pin
9
(No
Connection)
Pin 6 is connected only between multiple Whozz Calling? units and acts as a control line. When units are not
transmitting data this line resides at -9 VDC. Upon transmit, the unit pulls this line to +9 VDC. Other Whozz
Calling? units connected will detect this as a busy condition and will not transmit until the line returns to -9 VDC.
If connecting to a 25 pin serial port on the computer, we suggest using a 9 to 25 pin serial adapter. The pin outs on a
25 pin serial port are not the same as a 9 pin port. When the serial port is configured to “No Flow Control”, only
Transmit and Ground connections are required. Request to Send and Clear to Send connections will need to be
connected only if other serial flow control types are selected.
Computer DB25/M Serial Port
Monitoring Unit DB9/F
Pin
2
(Transmit)
Pin
2
(Transmit)
Pin
3
(Receive
)
Pin
3
(Receive)
Pin 4 (Request to Send)
Pin 7
(Internal
Pin 5 (Clear to Send)
Pin 8
Connection)
Pin
7
(Ground)
Pin
5
(Ground)