Teledesign Systems Inc TS4000EH Manuel D’Utilisation
TS4000 Radio Modem User’s Manual
Serial Port
12
The most common form of hardware flow control, and the one used by most full
duplex wired (as opposed to wireless) modems, is RTS/CTS. With RTS/CTS
flow control, RTS provides flow control for the DTE and CTS provides flow
control for the DCE. One problem with RTS/CTS flow control is that for many
half duplex modems (most wireless modems) the RTS signal is used to frame
transmit data going from the DTE to the DCE. This use of RTS conflicts with
using RTS for flow control of data to the DTE.
An alternative form of hardware flow control is DTR/DSR. With DTR/DSR flow
control, DTR provides the flow control for the DTE and DSR provides the flow
control for the DCE.
Software flow control uses characters sent over the data lines to control data
flow. These characters are sent along with the normal flow of data between the
DTE and DCE. There is typically one character that is used to stop the flow of
data and a different character to restart data flow. Software flow control can use
any characters to start and stop flow. However the most common characters
used are the ASCII XON (starts flow) and XOFF (stops flow) characters.
Because these are the most common characters used, software flow control is
often referred to as XON/XOFF flow control. The ASCII XON character is the
decimal character 17 (0x11 hex) and is also known as DC1 or Ctrl-Q. The ASCII
XOFF character is the decimal character 19 (0x13 hex) and is also known as
DC3 or Ctrl-S (See Appendix B - ASCII Character Set).
A problem with software flow control is that the normal data passed over the
communications link cannot include the flow control characters. If it does, the
flow of data will be incorrectly stopped or started. This limits the characters that
can be used by the host application and also prevents the sending of binary (all
character numbers) data.
The TS4000 serial ports are setup as DCEs (Data Communication Equipment).
The TS4000 with the standard case uses two 9 pin subminiature D connectors
with female pins for the serial ports. The TS4000 with the watertight case uses a
19 pin environmentally sealed LEMO connector (see Appendix A - Serial Port).
Serial port 1 can be configured for either RS-232 or TTL signal levels. To
change the signal levels, the modem must be opened and the four jumper plugs
next to the serial port connector set to the desired position (see Appendix A -
Serial Port, Appendix F - Internal Jumper Block).
Serial port 2 is always set for RS-232 signal levels.
The serial ports can be used with RS-485 signal levels through the use of an
external signal converter. These external signal converters can be obtained from
Teledesign.
The serial ports can be setup to provide different internal electrical connections
to the DTR, DSR and RI pins. To change the pin connections, the modem must
be opened and the jumper plugs next to the serial port connector set to the
desired position (see Appendix F - Internal Jumper Block).
duplex wired (as opposed to wireless) modems, is RTS/CTS. With RTS/CTS
flow control, RTS provides flow control for the DTE and CTS provides flow
control for the DCE. One problem with RTS/CTS flow control is that for many
half duplex modems (most wireless modems) the RTS signal is used to frame
transmit data going from the DTE to the DCE. This use of RTS conflicts with
using RTS for flow control of data to the DTE.
An alternative form of hardware flow control is DTR/DSR. With DTR/DSR flow
control, DTR provides the flow control for the DTE and DSR provides the flow
control for the DCE.
Software flow control uses characters sent over the data lines to control data
flow. These characters are sent along with the normal flow of data between the
DTE and DCE. There is typically one character that is used to stop the flow of
data and a different character to restart data flow. Software flow control can use
any characters to start and stop flow. However the most common characters
used are the ASCII XON (starts flow) and XOFF (stops flow) characters.
Because these are the most common characters used, software flow control is
often referred to as XON/XOFF flow control. The ASCII XON character is the
decimal character 17 (0x11 hex) and is also known as DC1 or Ctrl-Q. The ASCII
XOFF character is the decimal character 19 (0x13 hex) and is also known as
DC3 or Ctrl-S (See Appendix B - ASCII Character Set).
A problem with software flow control is that the normal data passed over the
communications link cannot include the flow control characters. If it does, the
flow of data will be incorrectly stopped or started. This limits the characters that
can be used by the host application and also prevents the sending of binary (all
character numbers) data.
The TS4000 serial ports are setup as DCEs (Data Communication Equipment).
The TS4000 with the standard case uses two 9 pin subminiature D connectors
with female pins for the serial ports. The TS4000 with the watertight case uses a
19 pin environmentally sealed LEMO connector (see Appendix A - Serial Port).
Serial port 1 can be configured for either RS-232 or TTL signal levels. To
change the signal levels, the modem must be opened and the four jumper plugs
next to the serial port connector set to the desired position (see Appendix A -
Serial Port, Appendix F - Internal Jumper Block).
Serial port 2 is always set for RS-232 signal levels.
The serial ports can be used with RS-485 signal levels through the use of an
external signal converter. These external signal converters can be obtained from
Teledesign.
The serial ports can be setup to provide different internal electrical connections
to the DTR, DSR and RI pins. To change the pin connections, the modem must
be opened and the jumper plugs next to the serial port connector set to the
desired position (see Appendix F - Internal Jumper Block).
Software Flow Control
Serial Port
Connector
Connector
Signal Levels
Serial Port 1
Serial Port 2
RS-485
Signal Options