Avocent ESP-4 MI, Инструкция по установке и эксплуатации, Страница: 63 / 80

Appendices
53
The right panel contains a graphical display of a DB-9 connector that indicates the state of the
control signals (red = low, green = high). The transmit and receive signals are always red. If control
signals change between samples, the colors will change at the start of the next sample display.
When samples are being collected, the area under the connector display contains a timestamp,
recorded in milliseconds at the beginning of each sample. During playback, timestamps are
displayed relative to the start time of the datascope session, not the time of day or date. The
accuracy of the timestamp is dependent on the Java Virtual Machine and the environment where
the datascope is being used.
The display advances in real time. Data from the next sample follows the last received data,
regardless of whether it was transmit or receive data.
Table B.1 describes each of the buttons in the lower left panel (from left to right).
The counters in the lower right panel display the number of saved samples, the number of buffered
receive data bytes and the number of buffered transmit data bytes.
The lower right panel will also contain a rotating circle when samples are being collected.
How it works
A data request is sent to the ESP-4 MI hub. The response may contain either receive or transmit
data, but not both; it will also contain status. If data is available, it is read and saved in a receive or
transmit data bucket. If there is no data available, the state of the control signals will be checked. If
there was a control signal change, the sample will be saved, even if there is no data to save.
Once a successful sample is collected, the most recent status is checked to see if there is any more
data pending to be read. If there is, the next sample is requested immediately. If not, a 50
millisecond delay is invoked before the next sample. This mitigates the amount of TCP traffic
generated by the datascope when the serial port is not busy.
Table B.1: ESP-View Utility Datascope Window Buttons
Button Description
Beginning (double left arrow with bar) Goes to the beginning of the table (view mode)
Reverse (double left arrow) Goes up 16 rows in the table (view mode)
Play (right arrow) Starts sample collection
Stop (square) Stops sample collection and closes the connection
Pause (two bars)
Stops sample collection but maintains the connection, waiting for a
command to resume or stop
Forward (double right arrow) Goes forward 16 rows in the table (view mode)
End (double right arrow with bar) Goes to the end of the table (view mode)