Hardware manual

5901 High Speed Dialup Modem Hardware Manual
October 19, 2007
12
Note: The 9VDC adapter connection cannot be used in Hazardous Locations.
4.2 RS-232 Serial Port
The RS-232 port is a 9-pin female D-sub-miniature connector (DE-9P) configured as Data
Communications Equipment (DCE). Figure 2: RS-232 Port Connector (DCE) and Table 1: RS-232
Connections describe the RS-232 connector.
2
RxD
3
TxD
7
RTS
8
CTS
1
DCD
6
DSR
4
DTR
9
5 V
5
Gnd
Figure 2: RS-232 Port Connector (DCE)
A description of each pin signal is shown in Table 1: RS-232 Connections. In this table a MARK is
a voltage of +3 volts or greater and a SPACE is a voltage of –3 volts or less.
Table 1: RS-232 Connections
Pin
Type
Description
Pin1
DCD
Output
This signal is at a MARK level when carrier is detected by the
modem on the receiver inputs.
The CD led is on for a MARK level.
Pin 2
RxD
Output
Data received by the modem is output on this pin. The level is
SPACE on standby and MARK for received data.
The RD LED is on for a MARK level.
Pin 3
TxD
Input
Data transmitted by the modem is input on this pin from the
DTE. The level is SPACE on standby and MARK for
transmitted data.
The TD LED is on for a MARK level.
Pin 4
DTR
Input
This signal indicates that the DTE is ready to receive data.
Pin 5
Ground
This pin is connected to the I/O system ground.
Pin 6
DSR
Output
This signal indicates the modem is ready to start
communication. It is always in a MARK state.
Pin 7
RTS
Input
This input must be a MARK for the modem to transmit data.
The DTE should set it to a MARK just before transmission of
data. The CTS output will be asserted when the modem is
ready to transmit data.
The RS LED is on for a MARK level.
Pin 8
CTS
Output
This output indicates the modem is ready to transmit data. A
MARK level indicates the modem is ready. The DTE should
wait for this signal before transmitting data.
The CS LED is on for a MARK level.