The name of the I/O server to which the I/O device is connected.

The name for the I/O device (31 characters maximum).

The name needs to be unique in the Citect SCADA system, unless the I/O device is defined in other I/O servers (to provide redundancy). If redundancy is used, the I/O device needs to then have the same I/O device number and address for each I/O Server. use different I/O device names for your primary and standby I/O devices, otherwise I/O device Cicode functions cannot differentiate between them.

A unique number for the I/O device (0-16383).

The number needs to be unique in the Citect SCADA system, unless the I/O device is defined in other I/O servers (to provide redundancy). If redundancy is used, the I/O device needs to then have the same I/O device number and address on each redundant I/O server. You may use the same device name, but if you want to use I/O device Cicode functions, it is easier to have different I/O device names.

The address of the I/O device (64 characters maximum).

The format of the address you enter in this field is determined by the type of I/O device (and protocol) used, as each has a different addressing strategy.

The protocol used to communicate to the I/O device (16 characters maximum).

Many I/O devices support multiple protocols, dependent on the communication method chosen.

The port on the board to which the I/O device is connected (31 characters maximum).

This is necessary to link the I/O device to the port. For example Board1_Port1.

Note: There is a limit of 255 COMx ports on a server. To avoid this limitation restricting the number of remote I/O devices you use, you can connect multiple remote I/O devices to the same port as long as communication details (telephone number, baud rate, data bits, stop bits and parity) are identical.

The type of I/O device redundancy used. The options are:

• Primary — Enable immediate use of this communications channel. This is the default mode if no mode is specified.
• Standby — This channel will remain unused until the I/O device configured with the primary channel becomes inoperative.
• StandbyWrite — This channel will remain unused until the I/O device configured with the primary channel becomes inoperative. Write requests sent to the primary channel are also sent to this channel.

To use Standby or StandbyWrite modes, you need to also configure a primary I/O device with the same I/O device name, number and address.

Note: Avoid using StandbyWrite mode for scheduled I/O devices because there is the possibility that the Standby I/O device write queue will not be cleaned up. When writing to a scheduled I/O device which it is not communicating, write requests are queued up until communication resumes. In case of using I/O device redundancy and StandbyWrite mode, Primary and Standby I/O devices have their own queues of pending write requests. If I/O device communication is controlled automatically by the communication schedule, then both queues are flushed when the schedule dial-time occurs. Where manual communication is controlled by the IODeviceControl Cicode function, only the Primary I/O device write queue is flushed and the Standby I/O device write queue will not be cleaned up.

Specifies the order standby devices are promoted in if a primary I/O device becomes inoperative during runtime (8 characters maximum).

If there is more than one standby I/O device configured for a cluster, you can use this field to give precedence to a particular standby device. If this field is left blank, priority will be automatically allocated to the device during project compilation, based on the priority settings of other standby devices and/or the order in which the devices were configured.

See I/O Device Promotion.

Specifies whether the I/O device runs in Memory mode. The default value is FALSE.

If you select TRUE, the I/O device will be created in memory and its values stored in memory at runtime. This may be useful if you are testing your system, before connecting physical I/O devices, as memory mode stops Citect SCADA from communicating with physical I/O devices. See Using Memory Mode.

Specify whether the I/O device is read-only. The default value is FALSE.

If you select TRUE, any attempt to write to a tag associated with the I/O device will be unsuccessful.

This setting controls the way in which redundant I/O device(s) configured with the same network number on different I/O servers activate communications to the physical device they represent.

When Exclusive is set to TRUE, only one I/O device (on one I/O server) will activate communications to the physical device at a time. The best available I/O device (online with the lowest priority) at a particular time will be chosen to actively communicate. When this I/O device is no longer the best available, it will deactivate, which will in turn trigger the best available I/O device on another server to activate.

When Exclusive is set to FALSE (default), the best available I/O device will typically be the only active I/O device; however this may not be enforced. When a different I/O device becomes the best it will activate immediately, without waiting for the other I/O device to deactivate. An I/O device that is not the best may also be forced into actively communicating with the physical device if a particular client can only communicate with the I/O server that I/O device is running on.

Note: The parameter [IOServer]PeerServerConnectTimeOut has been implemented so that on startup of an I/O server, all I/O devices with Exclusive set to TRUE will not be allowed to activate before the I/O server has successfully connected to its peers. This parameter defines how long an I/O server will wait until it ceases trying to connect to peer I/O servers.

Select TRUE or FALSE to specify whether or not the I/O device is linked to an external data source (see Linking Tags to an External Data Source).

If you link to an external data source, Citect SCADA is updated with any changes made to the external data source when a refresh is performed (see Refresh the Tags for a Linked I/O Device).

If you disconnect an existing link, you can choose to make a local copy of the tags in the database or you can delete them from Citect SCADA's variable tags database altogether.

If an I/O device is linked to an external data source the Database Type, External Database, Connection String, Tag Prefix and Live Update fields will be greyed out.

The format of the data referenced by the external data source.

The path and file name of the external data source for the I/O device.

If the Linked property is set to TRUE (and a Database Type has been specified), you can use the Browse button next to this field in the Property Grid to select and validate a database.

Alternatively, you can enter the IP address/directory, computer name, or the URL of a data server. For example:

• "C:\Work.CSV"
• "127.0.0.1"
• "139.2.4.41\HMI_SCADA"
• "http://www.abicom.com.au/main/scada"
• "\\coms\data\scada".

Enter a connection string to provide connection details for the data source. This is similar to an ODBC connection string. For example:

UserID = XXX; Password = YYY

or

ServerNode=111.2.3.44; Branch=XXX

Not every data source needs a connection string.

The prefix that will be inserted in front of the names of linked tags in Citect SCADA's variable tags database (for this I/O device only). To change the prefix, delete it first, perform a manual refresh, then add the new prefix.

Determines whether the linked tags in Citect SCADA's variable tags database will be updated when the external data source is changed.

This refresh will occur the first time you link to the data source, and then whenever you compile your project.

Without an automatic refresh, you will need to perform a manual refresh to update the linked tags in Citect SCADA (see Refresh the Tags for a Linked I/O Device).

Enables/disables the logging of writes to the I/O device. When enabled, writes are logged to the SYSLOG.DAT file in the logs folder of the Citect SCADAUser and Data folder selected during installation, also specified in the INI file as [CtEdit]Logs.

See Tag Functions for information about TagWriteEventQue and logging tag data.

Note: Logging writes to every I/O Device may slow communications as the Citect SCADA system will be writing large amounts of data to disk. However, logging of writes is useful when debugging a system.

Enables/disables data caching. When enabled, a cache of the I/O device's memory is retained at the I/O server, thus improving communications turn-around time.

Note: Data caching has to be enabled for scheduled I/O devices, but disabled for memory or disk I/O devices.

Specifies that tags for a particular device are continuously polled at a minimum background poll rate. The options are True or False. Set this field to True if you are operating on a slow network, with a slow device, or where tags may normally only be polled infrequently.

When Background Poll is set to True, specifies the minimum rate by which the device will be polled. You may select any predefined value from the drop-down list, or enter your own in the format of HH:MM:SS.

If a value is not entered, the default value of 30 seconds will be used.

The DataSource will send tag update value notifications to subscription clients after a pre-defined period of time expires. You may select any predefined value from the drop-down list, or enter your own in the format of HH:MM:SS.

If a value is not entered, the default value of 0 seconds will be used and no update value notifications will be sent.

Determines whether the I/O device is configured for scheduled communications. This is normally set using the Device Communications Wizard.

Note: If a schedule for a dial-up remote I/O device is not specified, the connection will be established at startup and will remain connected until shut-down.

See Scheduled Communications.

The I/O server will attempt to communicate with the I/O device at this time, and then at intervals as defined below. This time is merely a marker for Citect SCADA. If you run up your project after this time, the I/O server will not wait until the next day to begin communicating. It will operate as if your project had been running since before the start time.

The time between successive communication attempts. The period needs to be long relative to the driver's watchtime and the [Dial]WatchTime. If necessary, decrease these watchtimes or increase Period to make Period more than double the watchtimes.

Examples (based on a Synchronize at time of 10:00:00):

1. If you enter 12:00:00 in the Repeat every field, and start your project at 9 a.m., the I/O Server will communicate with the I/O Device at 10 a.m., then once every 12 hours after that, i.e. 10 p.m., then again at 10 a.m. of the following day, etc.
2. If you enter 12:00:00, and start your project at 4 p.m., the I/O Server will communicate with the I/O Server at 10 p.m., then again at 10 a.m. of the following day, and so on. The I/O Server will assume that communications were established at 10 a.m., so it continue as if they had been - communicating once every 12 hours after 10 a.m.
3. If you enter 3 days, and start your project at 9 a.m. on a Wednesday, the I/O Server will communicate with the I/O Device at 10 a.m., then once every 3 days after that, i.e. 10 a.m. on the following Saturday, then at 10 a.m. on the following Tuesday, etc.
4. If you enter the 6th of December in the Repeat every, and start your project during November, the I/O Server will communicate with the I/O Device at 10 a.m. on December 6, then again on December 6 of the following year, etc.

Select On Startup for a persistent connection. To disconnect a persistent connection, you need to call the IODeviceControl() function with type 8.

Cicode to be executed once communication with the I/O device has been established (and before any read or write requests are processed).

Cicode to be executed once communication with the I/O device has been terminated (and after read and write requests are processed).

Set to TRUE or FALSE to indicate if the persistence of the tag cache file is on or off. Default is TRUE and the data will be written to the XML file as described in "File Name" below. If one of the primary/standby I/O devices (identified by the same network number) has persistence set to FALSE, then every device has it turned off.

Indicates how often to persist the XML cache file to disk. Default is 10 minutes (00:10:00). Normally, the period used is the highest value specified for one of the primary/standby I/O devices (identified by the same network number).