Omni.Net Lite User’s Guide

 

Table 6 RS-232 Port: PPP/MP Parameters

 

 

 

 

LABEL

DESCRIPTION

 

 

 

 

Threshold of data

This field is not available if you select Enable Fixed MP.

 

loading to ADD/DROP

Set the maximum threshold in the ADD field and the minimum threshold in the

 

one channel

DROP field. The TA adds the second B-channel when traffic is above the

 

 

threshold and drops the second B-channel when traffic is below the threshold.

 

Persist time for

This field is not available if you select Enable Fixed MP.

 

monitoring threshold to

Set the time interval between calculating traffic load. The unit of a value is 5

 

add or drop one

seconds.

 

channel

 

 

2.6 RS-232 Port: V.24 Signal

The V.24 signal screen describes ways to treat data control signal for data transmitted via the RS-232 serial interface of the TA. You can also use this screen to configure how to control data flow between the computer and the TA.

2.6.1 RS-232 Flow Control

RS-232 Flow control is used to control data flow between devices, such as two modems or a computer and a modem, using a serial connection. Standard flow control protocols include hardware (RTS/CTS) flow control and software (XON/XOFF) flow control.

The RTS (Request To Send) and CTS (Clear to Send) lines of a RS-232 serial cable signal flow control handshaking. In the following example, A is a TA and B is a computer. For upstream traffic from B to A, when device A’s receive buffer is nearly full, it lowers the CTS line (the CTS LED is off) to signal device B to stop sending data. When A is ready for new incoming data, it raises the CTS signal (the CTS LED is on) to resume transmissiom. For downstream traffic from A to B, B sets the RTS line to have A stop or restart sending data.

Figure 11 CTS/RTS Handshake

Flow control can also be done using the XON character (by pressing Ctrl-Q on the keyboard) and XOFF characters (by pressing Ctrl-S) in a data stream. When a device receives an XOFF signal from another device, it suspends or stops data transmitting to that device until receiving an XON (Ctrl-Q) signal from the same device. An XOFF character is sent when the receive buffer is nearly full. An XON signal is sent when the buffer is no longer full. Binary files may contain these signal characters and cannot be sent with XON/XOFF flow control protocol.

Chapter 2 Using the Utility

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