The HART Protocol Token-Passing Data Link Layer Specification (HCF_SPEC-81 Revision 8.2) talks about Service Access Points (SAPs) that must be supported by a field device.
One of the Physical Layer SAPs is described as follows:
This SAP is passed back by the Physical Layer to confirm its ability to accept data for transmission, or to indicate it will accept no further data. In a modem implementation this SAP is usually mapped into the clear to send (CTS) signal from a modem."
Since the AD5700/AD5700-1 devices don't have a CTS signal, how can this requirement be implemented?
As implemented in the AD5700/AD5700-1 devices, the /RTS (Request To Send) digital input covers the two cases of:
From the SPEC-81 description, the role of the CTS (Clear To Send) signal is to confirm ability to accept data for transmission (which is what /RTS low does) or to indicate that it will accept no further transmission data (which is what /RTS high does).
Please let me know if you have any further questions.