44CHAPTER 3: CONFIGURING THE ETHERNET ADAPTER
After configuring the port mode, you also need to configure the following options:
■Line Length – As data arrives on the serial port it is accumulated in a buffer in the Ethernet Adapter. The Line length parameter sets the maximum size for this buffer. When the number of characters in the buffer reaches the Line length value the entire buffer is sent as the data in a single network packet.
The value of Line length can range from 1 to 1,408 bytes. The default value is 1,408.
Do not use values of line length less than 5 with a serial baud rate of 115,200 or greater.
■Timeout – Often serial data arrives in small bursts of characters. When the Ethernet Adapter receives a burst of data it will wait for a certain period of time for additional data to be received. If additional data is received, it is added to the receive buffer, and the Ethernet Adapter begins to wait again. If additional data is not received for longer than the period specified by the Timeout value, then the buffer of characters received is sent in a single network packet, and the process begins again.
The value of timeout is in units of milliseconds, and should be specified in 10 millisecond increments. The valid range for timeout is from 10 (0.01 second) to 65,000 (650 seconds). The default value is 10.
■Delimiters – Some serial devices transmit and receive data in a known structure. In these cases, there are often special characters that the transmitting device uses to indicate a complete message has been sent. These characters are referred to as delimiters. You can specify up to five different delimiting characters to the Ethernet Adapter. When the Ethernet Adapter adds one of these characters to its buffer of serial received characters, it will immediately send that buffer as a network packet.
The value of delimiters is specified as a list of hexadecimal values separated by spaces. You may specify up to five different delimiter values. For example, if you want to use the delimiter 41375, you must type the following hex values:
0x34 0x31 0x33 0x39 0x35
If you are unsure of the hex value for your delimiter character, consult the Web page www.asciitable.com for reference.
