User manual

IEC61131 User and Reference Manual
April 22, 2008
111
Protocol
Controller
com1
com2
com3
com4
SP Light
None
Xon/Xoff
None
Xon/Xoff
N/A
None
Ignore CTS
SP LP
None
Xon/Xoff
None
Xon/Xoff
None
Ignore CTS
N/A
SP 100
None
Xon/Xoff
None
Xon/Xoff
N/A
N/A
SP 32
None
Ignore CTS
None
Ignore
CTS
None
Ignore CTS
None
Ignore CTS
SP 32P
None
Ignore CTS
None
Ignore
CTS
N/A
None
Ignore CTS
SCADASense 4202 DR
SCADASense 4202 DS
N/A
None
None
Ignore CTS
N/A
SCADASense 4203 DR
SCADASense 4203 DS
N/A
None
None
N/A
SCADAPack 330/334
None
None
None
N/A
SCADAPack 350
None
None
None
N/A
The Port Type drop down menu selects the type of serial port. Valid selections depend on
the serial port and controller type as shown in the table below. The default selection is RS-
232. The options are as follows:
 RS-232: for a regular RS-232 connection.
 RS-232 Dial-up modem: If an external dial-up modem is used on the RS-232
connection.
This setting is required if the RTU is initiating a dialup connection through an external
modem connected to the corresponding serial port. For SCADASense controllers, the
digital input point can be used to provide a DCD signal, as required by the external modem.
 RS-232 Collision Avoidance: RS-232 connection with collision avoidance based on the
CD signal is available only when the DNP protocol type is selected on the serial
port, and the serial port supports handshaking.
When this flow control is enabled, the protocol uses the Carrier Detect (CD) signal provided
by the serial port to detect if the communication medium is in use. If it is, it waits until the
medium is free before transmitting.
Prior to transmitting each Data Link (DL) frame, the controller will test the CD line. If it is
active, a countdown equal to the DL timeout will be set and CD will be monitored every 100
ms throughout this countdown period. If the Data Link timeout is set to the minimum of 100
ms, the CD line will be tested once.
If the CD line reports inactive (line not in use), a frame will be transmitted immediately, and a
new DL timeout is started as normal. On the other hand, if CD remains active during the DL
timeout, the transmission attempt will fail. If a non-zero retry is configured in the Data Link
layer, the test will be repeated until the number of retries has been exhausted.
Note: RS-232 Collision Avoidance is supported only on serial ports which support
handshaking and whose protocol type is to DNP.
 RS-485: for a regular RS-485 connection.