Hello Everyone,
I write here because I have had some trouble with the NI 9871 which I use through the FPGA of cRIO 9038.
It is used to read NMEA sentences which come by pair every 10ms like the following example
$HEXYZ,+0188,000000.0,X,000000.0,Y,000000.0,Z,V*6F\r\n
$HERPY,+0188,-000.464,R,-00.056,P,+162.157,Y,V*47\r\n
To read them I built a state machine with the following steps:
1) check if there any is byte at port with the dedicated method every 2ms
2) if there is something, read port until I find the newline character
3) doing some parsing on the data
4) go to 1
At first it appears that the state machine was only able to read the first sentence of each pair. After some debugging I discover that when the state machine try to read the second sentence, it receives only "$HERPY,+0188" and there was nothing else to read. Then I realized that the string "$HEXYZ,+0188,000000.0,X,000000.0,Y,000000.0,Z,V*6F\r\n$HERPY,+0188" counts 64 bytes. I concluded that I was encountering some buffer overflow because I was trying the read a sentence of 103 character with a buffer of apparently 64 bytes.
I modified the state machine by removing the 2ms waiting time during the first step of the state machine and it seems to work now
Now the questions are:
1) Is there anybody who can confirms that the Rx buffer of the NI 9871 has a size of 64 bytes?
2) Is there any way to change this size ?
I thank you a lot in advance for any information about this topic
