Configuration Serial Port Configuration
4-9
Serial Data
Once a connection has been started, several different triggers can be used to transmit all accumulated serial
data to the host. These options are controlled with the Change Port [Portlist] Datasend command. The
datasend process used by the MSS balances network traffic with latency concerns.
One kind of trigger can be set by specifying a “timeout” condition of either the time since the last character
was received (with the Timeout Idle parameter) or the time since the current character burst was started
(with the Timeout Frame parameter). For example, to trigger data transmission 150 milliseconds after the
current character burst began, enter the following command:
Figure 4-20: Transmitting Serial Data with Trigger Delay
The example in Figure 4-20 can be visualized as:
x x x xxx xx (data) x x xx xxxxxxxx xx xxxx xx xxxx
|-----------------------------------------------------|
150 milliseconds transmit packet
Another option is to set a one- or two-character trigger that will cause the MSS to transmit the data. You
can also specify whether the trigger characters will be sent to the host as part of the serial data or whether
they should be discarded (the default). For example, the following commands will cause the accumulated
serial data to transmit as soon as the “Z” character is detected in the data stream and to send the matched
character (“Z”) to the host as part of that data.
Figure 4-21: Transmitting Serial Data with a Character Trigger
The example in Figure 4-21 can be visualized as:
x x x xxx xx (data) x x xx xxxxxxxx xx Z xx xxxx
|-------------------------------------------------|
transmit packet
The complete syntax of the Change Port [Portlist] Datasend command is described in the MSS Reference
Manual.
Baud Rate
The MSS and the attached serial device must agree on a speed, or baud rate, to use for the serial connection.
Valid baud rates for the MSS are 300, 600, 1200, 2400, 4800, 9600 (the default), 19200, 38400, 57600,
115200, and 230400 baud. The baud rate can be changed with the Change Port [Portlist] Speed command
followed by a baud rate number. The following example changes the baud rate for the second serial port.
Figure 4-22: Changing the Baud Rate
Local>> CHANGE PORT 1 DATASEND TIMEOUT FRAME 150
Local>> CHANGE PORT 1 DATASEND CHARACTER Z
Local>> CHANGE PORT 1 DATASEND SAVE 1
Local>> CHANGE PORT 2 SPEED 19200
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