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Clarification on RTS/CTS flow control (PH8) | Thales IoT Developer Community

May 14, 2014 - 4:05pm, 5365 views

Using the PH8 it seems that RTS/CTS flow control is not active by default, but practically mandatory. This is fine for us but the modem does not seem to be behaving according to my understanding of the V.24 standard. If I power up the modem and hold the RTS line high (Request to Send inactive) no messages are sent by the modem, not even the ^SYSSTART power up message. I have to send RTS low in order to allow any messages to come from the modem. As a result, it seems to me that the RTS is not actually equivalent to circuit 105 in the V.24 specification, as this circuit is intended to request the modem to wake up and prepare to receive data on TXD. Is it perhaps equivalent to circuit 133 (Ready For Receiving?) Can anyone tell me what the recommended use of the RTS pin is when sending messages to the modem? Looking forward to any suggestions, thanks!