43The way hardware-based flow control works in the EIA/TIA-232 standard involves two lines labeled RTS (“Request To Send”) and CTS (“Clear To Send”) connecting the two devices together on a point-to-point serial network in addition to the TD (“Transmitted Data”) and RD (“Received Data”) and signal ground lines. Like the TD and RD terminals which must be “crossed over” between devices such that the TD of one device connects to the RD of the other device and vice-versa, the RTS and CTS terminals of the two devices must be similarly crossed. The RTS is an output line while the CTS is an input, on both devices. When a device is able to receive data, it activates its RTS output line to request data. A device is not permitted to transmit data on its TD line until it is cleared to send data by an active state on its CTS input line.