Some PSTN outstations can use a number of PSTN channels to report alarm data to the ClearSCADA server. These channels are referred to as dial in channels as they are used when the outstation ‘dials in’ to the ClearSCADA server. The number of channels varies depending on the outstation type.
Use the fields on the PSTN tab of the associated Outstation Form to define the required Dial In properties. By default, the information in these fields is not set up when you first configure a new outstation.
The following Dial In Lines fields are displayed for outstations on many advanced drivers. For other common PSTN fields, see Define an Outstation’s PSTN Properties, and see Define Dial In Overactive Properties on a PSTN Outstation. For fields that are not described in any of these sections, see the driver-specific documentation.
Use this field to specify any prefix that needs including at the start of any dial in numbers. Include a number in this field, for example, if the outstation is connected to a local telephone exchange and an additional number (such as 9) is required to dial an external line. The prefix is added to any downloaded dial in Telephone Numbers, and removed from any uploaded numbers.
For each available line, use the Location combo box to define whether the line will be used by the outstation to contact the local ClearSCADA server, or another source:
The channel is used to communicate with the ClearSCADA server that contains the configuration for the outstation (that is, the ClearSCADA server on which you are configuring the PSTN outstation).
The channel is used to communicate with another source, for example, a handset. The sources that are supported differ, depending on the type of outstation.
If you are defining a line with a Local location, proceed to the Channel field.
If you are defining a line with a Remote location, proceed to the Telephone Number field.
If you are defining a line with a Local location, proceed to the Channel field.
If you are defining a line with a Remote location, proceed to the Telephone Number field.
Only available for lines that are set to Local. Use the field to specify the PSTN channel that is to be used to communicate with the ClearSCADA server. Use the browse button to display a Reference browse window and choose the required channel. If you are unsure which channels are used, please contact a system administrator, or refer to the system design.
You can only specify a PSTN Channel that is configured as a Dial In Only, or Dial In and Out line (a channel that is configured as Dial Out Only is reserved for the ClearSCADA server to dial out to an outstation). You specify a channel’s Dial In/Out functionality using the PSTN tab on the Channel Form (see Defining PSTN Settings for a Channel).
If your system uses a ‘hunting’ telephone exchange or similar, whereby a pool of PSTN lines share the same telephone number, specify any one of those lines in this field. (The exchange can be local to the site or be provided by a telecoms provider.)
ClearSCADA monitors the channels that are listed in the Channel fields, along with their dial in and dial out properties. If using a ‘hunting exchange’, ClearSCADA also monitors any other channels that share the same telephone number as those listed. Such monitoring is used to determine the state of the outstation. Provided that the outstation is healthy, and at least one channel with dial in capability is available, the outstation will be able to dial in to ClearSCADA when required.
Only available for lines that are set to Remote. Enter the telephone number of the remote source.
A particular ClearSCADA system has a number of PSTN lines. The properties of the lines, including their telephone numbers and dial in/out capability, are configured on the relevant PSTN Channel Forms:
(‘PSTN Channel C’ is a dedicated dial out line that the server can use to dial out to the outstations on the system.)
Several of the outstations on the system are able to dial in to ClearSCADA to report alarms. The properties on the PSTN tab of the relevant Outstation Forms are used to specify the PSTN line(s) that the outstations can use to dial in to ClearSCADA. The configuration of one of these outstations is as follows:
The ClearSCADA server monitors the status and dial in/out capability of its PSTN channels, to determine the communications status of each outstation. For the above PSTN outstation, when ClearSCADA is not actually communicating with, or attempting to establish communications with, the outstation via PSTN, the outstation’s status might be one of the following:
| Channel Status | Outstation State | Comments |
|---|---|---|
|
A, B, and C Healthy |
Available |
Channels A and B are available for dialing in to ClearSCADA. Channels A and C are available for dialing out. |
|
A Failed, B and C Healthy |
Available |
Channel B is available for dialing in and channel C for dialing out. |
|
B Failed, A and C Healthy |
Available |
Channel A is available for dialing in to ClearSCADA. Channels A and C are available for dialing out. |
|
C Failed, A and B Healthy |
Available |
Channels A and B are available for dialing in to ClearSCADA. Channel A is available for dialing out. |
|
A and B Failed, C Healthy |
Available (Outgoing Only) |
Channel C is available for dialing out. |
|
A and C Failed, B Healthy |
Available (Incoming Only) |
Channel B is available for dialing in. |
|
B and C Failed, A Healthy |
Available |
Channel A is available for dialing in or out. |
|
A, B, and C Failed |
All Channels Failed |
No PSTN channels are available. |
Further Information