Toshiba STRATA DK14 Installation And Maintenance Manual page 558

Peripheral Installation
PC/Data Communications Interface Units
Data Set Ready (DSR, Pin 6)
When connected to the communication channel and prepared to exchange control characters to
initiate data transmission, the DCE device sends the DSR signal (EIA circuit CC) to the DTE
device. If the PDIU DIP switch SW1-2 is set On, DSR will be On continuously; if the switch is set
Off, DSR follows DTR (if DSR is On, DTR is On, etc.) SW1-2 should be Off in most cases.
Data Carrier Detect (DCD, Pin 8)
The DCE device sends the DCD signal (DCD, Pin 8) when receiving the carrier signal on the line
side. Before transmitting or receiving data, most DTE devices require that the DCD be On. If the
carrier signal is removed by the remote end or lost due to a fault condition on the line, the DCE
notifies the DTE device by an Off condition with the DCD signal. The PDIU DIP switch SW1-2 is
set On to set the DCD On continuously. If set Off, the DCD signal will only be On when
connection between two DIUs is established and Off when a connection is not established. SW1-2
is set Off when the DTE/DCE uses the DTR/DSR signals for Ready/Busy flow control.
Data Terminal Ready (DTR, Pin 20)
The DTE device sends the DTR signal (EIA circuit CD) to the DCE device, prompting the DCE
device to open the communication line. The line is closed and the call disconnected when the DTE
device quits sending the DTR signal. DTR may be sent any time to indicate that the DTE is ready
to transmit or receive data. DIP switch SW1-2 should be set Off in most cases.
Ring Indicator (RI, Pin 22)
The RI signal (EIA circuit CE) is sent by the DCE device to the DTE device. Whenever the DCE
device receives a ringing signal on the line side, it turns the RI signal On. If RPCI or DIU DIP
switch SW1-3 is set On, the RI signal will be continuously On if ringing; if the switch is set Off,
the RI signal will be one second On/three seconds Off when the RPCI or DIU detects ringing
signal.
12-50
Strata DK I&M 6/00