“The CTS is proven to work well. Note that it goes “high” for only a few ms (while the buffer is emptied via RF) and then goes low again, when the module is then able to receive UART data.
One test you can do is to change the packet size (buffer size) to like 2 bytes and then send 128 bytes, then you will see the CTS going high after each 2nd byte, and if the host works properly all 128 bytes of data will come through 2 by 2 bytes (note that you must of course also configure your host Telnet of HyperTerminal of whatever to work in hardware handshake mode).
It is possible that your host must be configured for 2 stop bits in order to catch the CTS signal otherwise it might act too slow to the CTS going high. When everything is configured correct, we have sent large data files of several kB
via using the CTS signal for controlling the UART flow.
Last Update: October 10, 2017