WIZ127SR and RTS and baud rate 1843200 Bd

Question

Does RTS/CTS handshake work? I activate it for UART1 (I use firmware ver.1.0. and ConfigTool 1.0.0.1), 921.6 kBaud, 8 bit,N,1 and Nagle wait time 1 ms. When I sent 6000 byte into Rx input, I got only about 4000-5000 bytes from Ethernet (checked also directly with Wireshark) but RTS signal stays in log 1 ie. 3.3 V whole time. When I switched off nagle timer, I got whole data. I also test rate 1843200 Bd, it works but also lost some byte even without nagle timer and RTS remains unchanged again. So how does RTS work? According User’s manual V111 RTS go to 0 when input buffer is full. Does WIZ127SR support also 1843200 Bd speed? According specification it works only with 921 KBaud.

Janasek · Answer

My problem is simple - I need to sent serial data to WIZ127 as fast as possible, so I activate RTS/CTS handshake and I have a simple loop: wait for RTS=high=3.3 V, then sent a byte to module. It works well when I connect Ethernet port directly to PC - I can transfer some millions of bytes without any mistake. When I connect module through 100 Mbit switch into simple local network I sometimes lose data probably due traffic but I expect that when Ethernet is busy WIZ127 stops receiving from serial link by falling RTS down but RTS stays always high and I lose data.

ywkwon · Answer

Flow control works when the buffer overflow occurs. It looks in the your environment, buffer overflow does not have to occur, so that flow control does not occur. The WIZ127SR, the amount of processing is often internally. Therefore, if you transfer a lot of data at a time at high speed Baud Rate, there is a possibility that some bytes loss. Turn off all of the options that do not use like Debug message, NTP, DNS, and Serial Congifuration. And please try to test it a little down the Baud Rate.

Janasek · Answer

I understand that processor can be busy, but I suppose that when it can’t accept data for any reason, it sets RTS to 0, without this I think higher baud rates have no sense. Missing data is unacceptable for me.