Page Unit

Unit

The name of the I/O device defined in the project.

IO Server

The name of the I/O server that is servicing this I/O device.

Comment

A description of the I/O device.

Unit Network No

The I/O device number defined in the project.

PLC Number

The physical I/O device address defined in the project.

Port Name

The communication port to which the I/O device is connected.

Protocol

The protocol used for communication with the I/O device.

Unit Status

The status of the I/O device. Only I/O devices that are serviced by this I/O Server are shown, and their redundant I/O devices if page is shown in Verbose mode.

The unit status can be one of the following:

• RUNNING - Indicates that the communication link with the I/O device is good.

• STANDBY - Indicates that the communication link with the I/O device is good, but communication with that I/O device is currently being performed by another port. This port is in standby mode.

• STARTING - Indicates that the server is currently establishing a communication link (with the I/O device).

• STOPPING - Indicates that the server is currently relinquishing control of the communication link (with the I/O device).

• OFFLINE - Indicates that the server cannot establish a communication channel with the I/O device. If a standby port or server is available, Plant SCADA tries to communicate to the I/O device using that port.

• REMOTE - Indicates that the status of the I/O device is OK, but it is not currently connected.

Note: If running the Kernel on the I/O server, you will get the current status of the I/O device. If running the Kernel on a client elsewhere, you will get the last known status.

Primary

Indicates if the I/O device is configured to be in primary mode.

• Yes = Primary

• No = Standby.

If the I/O device is in primary mode, the server starts a communication channel with the I/O device as soon as the server is activated. If an I/O device is in standby mode, the I/O device remains inactive when the server starts (until a primary I/O device becomes inoperative).

Priority

The relative priority configured for this I/O device. This field is only relevant for redundant I/O devices.

The standby I/O device with the highest priority will take over from the primary when required, the next highest priority will take over from that device if required. Be aware that the highest priority will have the lowest priority value.

Generic Error

The last generic error code returned by the driver. Because most protocol drivers have their own special errors, they cannot be recognized by the I/O server. The drivers convert their special errors into generic errors that can be identified by the server.

Error Handle

This field is for internal diagnostics.

Driver Error

The driver-specific error code. Each driver has its own special error codes. Refer to the driver specific errors (for the particular protocol) for an explanation of each of the error codes.

Error Message

The alert message associated with the generic error code.

Error Count

The total number of errors from the I/O device.

Restarts

The number of times the server has tried to establish a connection with the I/O device. This number is normally 1, because the server establishes a connection at startup. If this field displays a number greater than 1, there is a problem with the communication channel.

Response Times

The time taken by the driver to process read and write requests (i.e. the time taken to process a single read or write operation to the I/O device). This time depends only on the physical response time of the I/O device, because no queue waiting time is included. This field reflects any tuning of the communication channel (for example doubling the baud rate will half the response time). The average, minimum, and maximum times are displayed.

Note: One I/O device with a slow response may slow down your entire system. For example, if you have an I/O device with a response of 2000 ms, any pages in your system that use data from that device, will have a minimum update time of 2000 ms.

Cached

This field indicates if the I/O device data is cached. Caching may impact communications with the physical device.

Cache Timeout

If the I/O device is cached, this field displays the cache timeout value. Data is held in the cache for this timeout period before being discarded and re-read from the I/O device. Only read data is cached.

Blocking Constant

The current blocking constant value for this I/O device, as specified in the protocol. This value influences how requested I/O is blocked together.

Dial-up Connection

The status and history of the dial-up connection.

• SUCCESS - The number of successful dial-up attempts.

• FAIL - The number of unsuccessful dial-up attempts.

• TOTAL - The total number of dial-up attempts.

• NEXT - The time of the next scheduled dial-up attempt.

Total Connect Time

Accumulated time over all connections.

Average Connect Time

Average time per connection.

Subscription Management

<In Progress>

Unit State

An I/O device can have <n> level redundancy with a Primary and multiple Standbys on one or more I/O servers. The Unit State for a specific I/O device can be one of the following:

• GLOBAL ACTIVE - The highest priority redundant online I/O device, across all I/O servers. Be aware that the highest priority will have the lowest priority value.

• LOCAL ACTIVE - The highest priority redundant online I/O device, on this I/O server.

• INACTIVE - The I/O device is either offline, or online and not Local Active.

• FORCE ACTIVE - A Local Active unit forced into operation when receiving subscription requests.

Active Subscriptions

The number of client tag subscriptions serviced for this I/O device.

Poll Reads Total

The accumulated number of poll reads issued to physical device to service tag subscriptions.