<Ul> <Li> The large voltage swings and requirement for positive and negative supplies increases power consumption of the interface and complicates power supply design . The voltage swing requirement also limits the upper speed of a compatible interface . </Li> <Li> Single - ended signaling referred to a common signal ground limits the noise immunity and transmission distance . </Li> <Li> Multi-drop connection among more than two devices is not defined . While multi-drop "work - arounds" have been devised, they have limitations in speed and compatibility . </Li> <Li> The standard does not address the possibility of connecting a DTE directly to a DTE, or a DCE to a DCE . Null modem cables can be used to achieve these connections, but these are not defined by the standard, and some such cables use different connections than others . </Li> <Li> The definitions of the two ends of the link are asymmetric . This makes the assignment of the role of a newly developed device problematic; the designer must decide on either a DTE - like or DCE - like interface and which connector pin assignments to use . </Li> <Li> The handshaking and control lines of the interface are intended for the setup and takedown of a dial - up communication circuit; in particular, the use of handshake lines for flow control is not reliably implemented in many devices . </Li> <Li> No method is specified for sending power to a device . While a small amount of current can be extracted from the DTR and RTS lines, this is only suitable for low - power devices such as mice . </Li> <Li> The 25 - pin D - sub connector recommended in the standard is large compared to current practice . </Li> </Ul> <Li> The large voltage swings and requirement for positive and negative supplies increases power consumption of the interface and complicates power supply design . The voltage swing requirement also limits the upper speed of a compatible interface . </Li> <Li> Single - ended signaling referred to a common signal ground limits the noise immunity and transmission distance . </Li> <Li> Multi-drop connection among more than two devices is not defined . While multi-drop "work - arounds" have been devised, they have limitations in speed and compatibility . </Li>

What is the eia/tia 232 protocol concerned with