Multitech MT2834BAI, MT1432BA manual Received Data Pin 3, RD BB, Request To Send Pin 4, RTS CA

Appendix J - RS-232C Interface Specifications

Functional Description of RS-232C Signals:

Transmitted Data - Pin 2, SD (BA)

Direction: to modem

Signals on this circuit are generated by the customer's terminal and transferred to the transmitter of the modem. A positive signal is a space (binary 0) and a negative signal is a mark (binary 1). The transmitting terminal should hold this line in the marking state when no data is being transmitted, including intervals between characters or words. The TRANSMIT (XMT) LED indicates the status of this circuit.

Received Data - Pin 3, RD (BB)

Direction: from modem

The lead is the data output of the modem. Data signals received from the remote modem are presented on this line. When no carrier signal is being received (pin 8 negative), this line will be forced into a marking condition. The RECEIVE (RCV) LED indicates the status of this signal.

Request To Send - Pin 4, RTS (CA)

Direction: to modem

The RTS signal indicates to the modem that the computer or terminal has data that it wants to transmit.

Clear To Send - Pin 5, CTS (CB)

Direction: from modem

The CTS line indicates to the terminal that the modem will transmit any data present on the Transmit Data line (pin 2).

Data Set Ready - Pin 6, DSR (CC)

Direction: from modem

DSR On indicates that the modem is in the data mode and is connected to the communications channel. This signal will be on during analog-loop-test mode.

Signal Ground - Pin 7, SG (AB)

The SG lead is connected to signal ground of the modem. It establishes the common ground reference for all other interface signals.

Data Carrier Detect - Pin 8, CD (CF)

Direction: from modem

DCD On (positive voltage) indicates that data carrier has been received from the other modem. This circuit will not normally turn on in the presence of message circuit noise or out-of-band signals. There is a one second delay between when the carrier tone has been detected and when the CD circuit is turned on.

This signal goes off if received data carrier falls below the receiver threshold for more than 37 mSec. When CD is off, the Received Data circuit (pin 3) is held to the marking state.

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