Posted on December 02, 2014 at 21:24Hello,
I designed my own application starting from VirtualComport_loopback example project.
I have a modbus client protocol running on USB and using CDC_Send_DATA() and CDC_Receive_DATA() send and get data from PC virtual comm. port.
I have problems with modbus commands with read and/or writes longer that 64 bytes. I resolved the output problem splitting the answer into 64 bytes blocks. I wonder if I can do the same thing with input or increase the input buffer to 256 bytes (max. protocol message length).
Here is some piece of code:
uint32_t CDC_Send_DATA (uint8_t *ptrBuffer, uint16_t Send_length)
{
uint8_t len;
uint8_t *buff = ptrBuffer;
packet_sent = 0;
while (Send_length)
{
if (Send_length < 64) len = Send_length;
else len = 64;
/* send packet to PMA*/
UserToPMABufferCopy((unsigned char*)buff, ENDP1_TXADDR, len);
SetEPTxCount(ENDP1, len);
SetEPTxValid(ENDP1);
Send_length -= len;
buff += len;
Delay_10ms(2);
}
return 1;
}
