Rockwell Automation DAG6.5.8 APPLICATION GUIDE SCADA SYSTEM - Manual (Page 143)

Publication AG-UM008C-EN-P - February 2005
Configuring SLC 5/03, 5/04, and 5/05 Processors 4-5
Modem Control Line
Operation The following explains the operation of the SLC 5/03, 5/04 and 5/05
processors when you configure the RS-232 channel for the following
applications.
DF1 Full-Duplex
When configured for DF1 full-duplex, the following control line
operation takes effect:
No Handshaking Selected
DTR is always active (high) and RTS is always inactive (low).
Receptions and transmissions take place regardless of the states of
DSR, CTS, or DCD inputs. Only make this selection when the SLC
5/03, 5/04 and 5/05 processors are directly connected to another
device that does not require handshaking signals.
Full-Duplex Modem Selected
DTR and RTS are always active except:
•
If DSR goes inactive, both DTR and RTS are dropped for 1 to 2
seconds, then reactivated. The modem lost bit (S:5/14) is turned
on immediately. While DSR is inactive, the state of DCD is
ignored. Neither receptions nor transmissions are performed.
•
If DCD goes inactive while DSR is active, then receptions are not
allowed. If DCD remains inactive for 9 to 10 seconds, DTR is set
inactive. At this point, the modem lost bit is also set. If DSR
remains active, DTR is raised again in 5 to 6 seconds.
Reception requires DSR and DCD to be active. Transmission requires
all three inputs (CTS, DCD, and DSR) to be active. Whenever DSR and
DCD are both active, the modem lost bit is reset.