To Set SWB 8
Pass breaks ON
Ignore breaks OFF
Lead Pass-Through
This function allows the COS II either to pass
hardware-handshake leads to connected devices, or
to block them. If they are blocked, the leads will still
be used to regulate the 8K internal buffer of the
Switch. The following table shows the behavior of
the COS II for different combinations of devices.
Master Slave Leads passed
DTE DTE Master CTS to slave DTR
Slave CTS to master DTR
DTE DCE Master CTS to slave CTS
Slave DTR to master DTR
DCE DTE Master DTR to slave DTR
Slave CTS to master CTS
DCE DCE Master DTR to slave CTS
Slave DTR to master CTS
To pass or block leads, use SWC 8.
To Set SWC 8
Pass leads ON
To block leads OFF
Text or Graphics Mode
SWD 8 and SWE 8 determine whether the COS II is
in Graphics Mode or Text Mode. These same
switches also govern the device that will signal the
pause when the Switch is in Graphics Mode. (For
more information on Text and Graphics Modes, see
Sections 4.4 and 4.5).
When set for graphics, the COS II can register (1)
only pauses in data coming from the master port,
(2) only pauses in data coming from a slave port,
(3) or pauses in data from all ports, either master or
slave. Use ththis chart to configure the switch
properly:
Set Set
For SWD 8 SWE 8
Text Mode OFF OFF
Graphics Mode,
pause from master ON ON
Graphics Mode,
pause from slave OFF ON
Graphics Mode,
pause from either ON OFF
CODE OPERATED SWITCH II
16
3.8. Configuring Ports for DTE or DCE
A pair of DIP shunts lies behind each DB25
connector on both the main board and the
Expansion Unit. The pair eliminates the need for
crossover cable to connect devices to the Switch.
You can use standard straight-through cable may be
used instead, with the DIP shunts acting as
crossovers.
A shunt jumper lies in each shunt marked DCE.
To change the port configuration to DTE, just pry
the jumper gently from its current shunt, and insert
it in the DTE DIP shunt.
The chart below provides the signal direction for
the main RS-232 lines.
Configured as Signal direction Configured as
DTE Port DCE Port
TXD (2) Output from unit RXD(3)
RXD (3) Input to unit TXD (2)
RTS (4) Output from unit DCD (8)
CTS (5) Input to unit DTR (20)
N/A Output from unit DSR (6)
DCD (8) Input to unit RTS (4)
DTR (20) Output from unit CTS (5)
RI (22) Input to unit N/A
