Chapter 4 - Control from the Supervisory Port HCD-E1
Installation & Operation Manual
4-4 Hardware Requirements 11/01/00 19:23
Request to Send (RTS)
The RTS line is normally ON (active) when the supervision terminal is in
session.
When the RTS line is OFF (inactive), HCD-E1 interprets any data received
from the terminal on the TD line as MARK.
Clear to Send (CTS)
The state of the CTS line is determined by the CTS parameter:
ON The CTS line is always ON (active).
=RTS The CTS line follows the RTS line.
Data Carrier Detect (DCD)
The state of the DCD line depends on the communication address (node
number):
• When the node number is 0, the DCD line is always ON (active).
• When a non-zero node number is used, the DCD becomes ON (active)
when data is detected on the RD line, provided HCD-E1 recognizes its
own address in the data stream.
To simulate DTE operation, the delay between these events can be set by
the user (by means of the DCD_DEL parameter).
Ring Indication (RI)
The RI line is used only with dial-up modems (INT=DTE).
The RI line is normally OFF (inactive), and switches to the ON (active) state
when the modem attached to the HCD-E1 front-panel CONTROL DCE
connector detects an incoming call (see also the DSR Line section).
Data Set Ready (DSR)
• Usually, the DSR line is configured to track the DTR line. In this case, if
the control port interface is DTE, the DSR line will be set to ON for five
seconds when the RI line is ON while the DTR line is OFF.
• If the control port interface is DCE, the DSR line can also be configured
to be continuously ON. However, if the DTR line switches to OFF, the
DSR line will also switch to OFF for 5 seconds.
In addition, HCD-E1 always sets DSR OFF (inactive) for 5 seconds when the
EXIT command is executed, or the disconnect time-out expires.