B&B Electronics RS-232 Baud Rate Converter CE 232BRC - Manual (Page 6)

232BRC-1005 Manual 9
B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax 815-433-5104
B&B Electronics – Westlink Commercial Park – Oranmore, Galway, Ireland – Ph +353 91 792444 – Fax +353 91 792445
Software(XON/XOFF)
Handshaking:
Each port can be independently configured for software
handshaking. Software handshaking is normally used in
communications links where the main data stream is one way, such
as to a printer. The main sending device is expected to hold off its
data when it receives the XOFF(13 Hex) character, and resume
sending when it receives an XON(11 Hex). The main receiving
device is expected to send the XOFF character if the buffer is full or
it otherwise needs to hold off the data.
The 232BRC can be set to emulate either the main sending
device or the receiving device. It can either supply the XON/XOFF
handshake or stop sending data with the XON/XOFF. The port
would normally be set to supply the XON/XOFF characters if it is
connected to a fast sending device. It would be set to receive the
XON/XOFF handshaking if the port is connected to the slower
receiving device.
Port Connections
In order to determine the proper port connections to the
232BRC, it is necessary to have a basic understanding of the terms
DCE and DTE. RS-232 was designed, using DB-25 connectors, for
connecting a DTE (Data Terminal Equipment) device to a DCE
(Data Communication Equipment) device. Each device will have
inputs on pins that correspond to outputs on the same pins of the
other device. For example, a DTE device will transmit data out on
pin 2 (on a DB-25) and a DCE device will receive data in on pin 2
(on a DB-25). IBM PCs and serial printers are DTE devices,
modems are DCE devices.
Originally the RS-232 Standard specified only a 25 pin, D-sub
connector. Since then, the use of a 9 pin, D-sub supporting only a
portion of the original RS-232 signals has been used extensively,
starting with the IBM PC and migrating into other peripherals. The
pin outs for this 9 pin connector have since become the EIA/TIA 574
Standard. This standard specifies a DTE device that transmits on
pin 3 and receives on pin 2, with the DCE having the opposite
configuration. Figure 2.1 shows the signal direction for 25 pin and 9
pin devices configured as a DTE and DCE.
232BRC-1005 Manual
B&B Electronics Mfg Co Inc – 707 Dayton Rd - PO Box 1040 - Ottawa IL 61350 - Ph 815-433-5100 - Fax 815-433-5104
B&B Electronics – Westlink Commercial Park – Oranmore, Galway, Ireland – Ph +353 91 792444 – Fax +353 91 792445
10
Figure 2.1. DTE/DCE Port Diagrams
Port A Connections
Port A of the 232BRC is a 9 pin, female D-sub connector
configured as a DCE. This provides direct connection to an IBM PC
compatible or other DTE device. If it is necessary to connect Port A
to a modem or other device configured as a DCE, a null modem
adapter or cable is needed.
See Appendix A for a complete set of connection tables to the
232BRC ports.
Port B Connections
Port B of the 232BRC is a 9 pin male D-sub connector configured
as a DTE. This provides direct connection to a modem or other DCE
device. If it is necessary to connect Port B to a PC or other device
configured as a DTE, a null modem adapter or cable is needed.
See Appendix A for a complete set of connection tables to the
232BRC ports.
Power Connections
Power to the 232BRC is supplied through the 2.5mm Phono jack
on the side of the unit (Tip Positive). The 232BRC has an integrated
regulator, allowing it to operate on any supply voltage between +12
to +17 VDC. The 232BRC will draw 60 mA max.
25 Pin DTE
2 (TD)
4 (RTS)
3 (RD)
5 (CTS)
20 (DTR)
6 (DSR)
8 (DCD)
7 (GND)
9 Pin DTE
3 (TD)
7 (RTS)
2 (RD)
8 (CTS)
4 (DTR)
6 (DSR)
1 (DCD)
5 (GND)
25 Pin DCE
2 (TD)
4 (RTS)
3 (RD)
5 (CTS)
20 (DTR)
6 (DSR)
8 (DCD)
7 (GND)
9 Pin DCE
3 (TD)
7 (RTS)
2 (RD)
8 (CTS)
4 (DTR)
6 (DSR)
1 (DCD)
5 (GND)
T
T
T
T
T
T
T
T
T
T T
T
T
T
R
R
R
R
R
R
R
R
R
R
R R
R
R
T = RS-232 Transmitter R = RS-232 Receiver