Hi,
We are using an EG21-G module in an embedded environment. When utilizing a TCP-client connection and sending large packets (say greater than 250 bytes), the received packet at the other end does not match the original transmitted packet. There are always 3 bytes toward the end of the packet that have been overwritten with '0’s. We are using transparent access mode and the data is simply squirted out of the UART port. We don’t have any issues with packets less than say 200 bytes.
I can transmit the same packet over another UART to a serial terminal app, and the received data matches.
Here is part of the command configuration sequence:
AT+QICSGP=1,1,“internet”,“web”,“web”
OK
AT+QICFG=“transpktsize”,100;+QICFG=“transwaittm”,2;+QICFG=“tcp/accept”,0
OK
AT+QICSGP=1,1,“internet”,“web”,“web”
OK
AT+QIACT=1
OK
AT+QIOPEN=1,1,“TCP”,“c11mlt.com”,19000,0,2 // 2=transparent access mode
CONNECT
At this point, sending a packet through the UART works for packets of 200ish bytes or less, but with larger packets, there are always 3 bytes that seem to be overwritten/zeroed. Using wireshark at the receiving end confirms that the 3 bytes have already been altered when arriving.
Any ideas?