A Sierra Monitor Company
Driver Manual
(Supplement to the FieldServer Instruction Manual)
FS-8704-11 Telnet
APPLICABILITY & EFFECTIVITY
Effective for all systems manufactured after May 1, 2001
Driver Version
1.00b
Rev 1
Document revision
FS-8704-11 Telnet Driver Manual
Page 1 of 6
1.
Introduction
The Telnet driver allows a user to connect to the FieldServer using a standard Telnet client
(such as the Windows Telnet client). A command prompt is provided which allows the user to
request specific driver functions. Presently, the following functions are implemented:
1. help / ?: lists available commands and states their functions.
2. port: this allows the user to take over a serial port.
3. linefeed: this allows the user to control sending and receiving of line feeds in association
with carriage returns.
4. echo: allows the user to determine whether characters typed into the Telnet terminal
should be echoed by the FieldServer.
5. verbose: allows the user to determine the level of detail of diagnostic messages.
6. tab: allows the user to select substitution of received tab characters by space characters
The driver will support up to 5 concurrent Telnet sessions but will not allow two sessions to
control the same serial port.
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2.
Configuring the Telnet driver
To use the Telnet driver, the configuration (*.csv) file in use must resemble the following example:
// Set up common information
FieldServer
Title
Telnet Server
Adapters
Adapter, Protocol, Username, Password, autoconnect_port, autoconnect_mode,
N1,
session_timeout
60s
TLN,
Joe,
Secret,
R1,
Text,
Adapters
Adapter,protocol
N1,SMT
//
Set up the TLN Server side
Ports
Port
R1
R2
P1
Baud
9600
9600
9600
9600
Parity
None
None
None
None
P2
// examples of virtual comports
VS1
VC1
-
-
-
-
Note that the Telnet Driver will only be able to connect to ports that have been declared in the configuration file.
FS-8704-11 Telnet Driver Manual
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3.
Optional Configuration Items
Autoconnect Port
3.1.
If a port is specified in the autoconnect port field, the first Telnet session to connect to the
FieldServer will immediately be connected to the specified port (see Using Serial Port
Capture below). Any further simultaneous Telnet sessions will see the usual command
prompt.
3.2.
Autoconnect Mode
Two modes, Text and Binary, are available for use with Autoconnect Ports. Text mode is
optimized for manual use when using Telnet to communicate with a serial device that
presents a user interface (such as a text driven menu screen). This allows the user to
customize how tabs and linefeeds are sent and received. Also, the user can quit a port
capture by hitting Ctrl-C.
If the intention is to run a binary serial protocol over a Telnet connection, the Binary mode
must be specified. This does not modify the data stream in any way.
3.3.
Login
If desired, a username and password can be set in the csv file to restrict access to all
functions modifying the operation of the Telnet driver, e.g. port, linefeed, tab. The Login
command will prompt the user for the username and password before these commands may
be used.
3.4.
Timeout
A timeout can be set to close the Telnet session and its TCP connection after the specified
period of inactivity. Specify the timeout in seconds in the session_timeout field.
It is important to specify the session_timeout if the FieldServer is mainly used as a serial
protocol client continually communicating with the device. Under these circumstances, if a
Telnet session captures the serial port, the protocol driver is put on hold until the port is
released. If the user forgets to release the port and leaves the Telnet session connected, the
protocol driver on the FieldServer can never resume communications with the device, and
the bridge data is never updated. If the session_timeout is set, then a period of inactivity will
cause the port to be released and the Telnet session to be closed, so that the protocol driver
can resume its communication activity.
FS-8704-11 Telnet Driver Manual
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4.
Using the Serial Port Capture
Manual Serial Port Capture
4.1.
•
•
•
Once the FieldServer is up and running, connect to it using its IP address.
Type port <Enter>
When prompted, enter the name of the port to be captured (e.g. P8 <Enter>). The
driver will check if the desired port has been initialized by a “port” statement in the
configuration file. If the port has been initialized and is available, the driver will wait
for any current polls to finish, and will then print “Connected” to indicate that the port
is now under the control of the Telnet client. If a device is connected to the captured
serial port, you can now communicate with it as if you had a direct serial connection.
To disconnect the port from the Telnet session, press Ctrl-C. This will also work
while the driver is still waiting for an active poll to complete.
•
•
To terminate the Telnet session, close the Telnet client.
Notes:
1. If a port has been manually captured in one Telnet session, it will not be available to
any other Telnet sessions. Other sessions attempting to capture the port will be
returned to the command prompt with an error message. To release a port, the
connected Telnet session must be disconnected.
2. Capturing a port makes the port unavailable to any protocol driver on the FieldServer
that might have been communicating with the device. Refer to the comments on
session_timeout above on how to prevent an indefinite lockout if a Telnet session
with a port capture is forgotten on.
3. A Serial connection needs to be specified before defining the Telnet connection
(which has autoconnect_port) or else the FieldServer will give system error.
Example
Not Correct:
Connections
Adapter,
N1,
Protocol,
TLN,
Autoconnect_port
P1
Correct:
Connections
Adapter,
P1,
Baud,
9600,
Timeout,
10s,
Protocol
-
Connections
Adapter,
N1,
Protocol,
TLN,
Autoconnect_port
P1
FS-8704-11 Telnet Driver Manual
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4.2.
Autoconnect Serial Port Capture and Multiple Telnet Sessions
If an autoconnect port has been specified, a new Telnet session to the FieldServer will
automatically be connected to the specified port (in binary or text mode as specified). This
raises a potential conflict if there is already an existing session autoconnected to that port.
The FieldServer resolves this by terminating the original Telnet session, so that new session
is not locked out.
In text mode it is possible to quit out of a port autoconnect by hitting Ctrl-C; this session then
receives a Telnet command prompt. If this is done, the next new Telnet connection that is
made to the FieldServer will connect to the autoconnect port without affecting the first
session.
5.
Setting the Linefeed Options
Linefeed sending refers to the transmission of linefeeds generated by the Telnet user to a
comport he may be connected to.
Linefeed receiving refers to the option of inserting a linefeed into the data stream received
from a comport whenever a carriage return has been received.
•
•
•
Once the FieldServer is up and running, connect to it using its IP address.
Type linefeed <Enter>
When prompted, enter the desired state for linefeed sending and receiving (on/off
<Enter>).
•
To keep the current setting, just hit <Enter>.
6.
Setting the Echo Option
This option determines whether or not the FieldServer echoes characters typed into a Telnet
terminal.
•
•
•
At the Telnet prompt, type echo <Enter>
When prompted, enter the desired setting (on/off <Enter>).
To keep the current setting, just hit <Enter>.
7.
8.
Setting the Tab Option
This option determines whether or not the FieldServer replaces incoming tab characters with
spaces during port capture.
•
•
•
At the Telnet prompt, type tab <Enter>
When prompted, enter the desired setting (on/off <Enter>).
To keep the current setting, just hit <Enter>.
Setting the Verbose Option
This option determines the level of detail of diagnostic messages printed to the Telnet client.
There are three levels: 0 – not verbose; 1 – medium verbose; 2 – verbose.
•
•
•
At the Telnet prompt, type verbose <Enter>
When prompted, enter the desired setting (0/1/2 <Enter>).
To keep the current setting, just hit <Enter>.
FS-8704-11 Telnet Driver Manual
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9.
Running Serial Protocols over Telnet using Virtual Ports
The Telnet driver can be used to run serial protocols over TCP. To connect the Telnet driver to
a serial driver, use virtual comports. Virtual comports are software emulations of real comports,
and are connected in pairs. These connected pairs are ports VC1 and VS1, VC2 and VS2, VC3
and VS3, VC4 and VS4, and VC5 and VS5. Anything written to the port VCx will be received at
the port VSx, and vice versa. Note that autoconnect mode does not modify the data passing
through in any way; it overrides any linefeed or tab options that might have been set.
Serial ports on two FieldServers may be connected over TCP in this way, using a Telnet client
on one end and a Telnet server on the other. The client is configured to connect to the server
using Telnet, and both client and server autoconnect to the desired serial ports on the
respective FieldServers. The two serial ports are then transparently linked.
10.
Limitations
The Telnet driver will only capture ports that have been specified in the configuration file
used by the FieldServer. It will use the specified port parameters (baud rate, start/data/stop
bits, parity), or FieldServer defaults where these have not been specified.
11.
Revision History
Driver
Version Revision
Document
Date
Resp Comment
09/05/02
09/06/02
7/23/03
1.00
1.00
1.00
0
1
2
JCE
MF
JD
JCE-Created Document
MF-Reformatted Document
Releasing
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