3-2 Caution on the communication buffer size
3-2-1
host to EJ-41U
The temporary FIFO buffer, which pools serially received data, can only store 64 bites.
Accordingly, when the software flow control is activated, if the host does not respond, the FIFO
buffer will overflow. To analyze commands, the temporary memory buffer of the packet data has
256 bytes available. They are transferred from the FIFO buffer to the stand-by buffer
spontaneously. This does not mean that 1 line ends with only 64 characters!
3-2-2
EJ-41U to host
The FIFO buffer for the data that is to be transferred to the host, such as the received packet data
or echo back, has 720 bites available. If such data exceeds 720 bites, the received packet will be
discarded. In such cases, it communicates to the destination asking to wait for the transfer of
data. Or the retry can be used to request the data be sent again. AX.25 protocol makes it possible
to receive complete data but it may take time. However, data such as beacons may not be re-
captured. Please take note of the following to avoid over-flow:
(1)
Do not send XOFF (Ctrl+S) from the host and leave in that state it for a long time.
Process the display pause in the shortest possible time.
(2)
Do not key input while FLOW command is on (without hitting the ENTER key).
Hit enter key and start the display immediately. Or set FLOW off to avoid a pause.
If the echo command is on, both echo and received data will be displayed which can cause
confusion. This is avoidable if the host application can be activated with echo command off.
(3)
Do not transmit to the host large data such as monitor related output.
Do not send uncommon data for normal communications, such as debug data. It eliminates a
line of overflow monitor output.
3-3
Commands
3-3-1
AWLEN command
Abbrev. AW default 8 parameter 7/8 example AW 8
This is used to set the data length for serial communication with the host.
7 stands for 7 bites, 8 for 8 bites. Restart is required using RESTART command, or restart when
the back-up is made.
3-3-2
Parity command
Abbrev. PAR default 0 Parameter 0 to 3 example PAR 0
This is used to set the parity between the host and serial communication.
[0],[2] No parity
[1]
odd parity
[2]
even parity
Restart is required using RESTART command, or restart when the back-up is made.