TM 5-3895-374-24-2 955-257 PIN MNEMONIC SIGNAL DESCRIPTION 5 CTS Clear to This line must be made active by the host in Send order for the controller to send data unless handshake lines are inactive (see switch settings, Section 5.8). 6 DSR Data Set Since the controller is a respond only device Ready and does not initiate correspondence, the controller assumes that the host is ready to receive if the clear to send line is active, and does not monitor this line. 7 SG Signal This line provides a common signal connection Ground for the RS232C environment.  It is also used as a ground reference for the power supplied by user for isolated configurations. 8 DTR- Data Return line for Data Terminal Ready signal Terminal (PIN 20) used with RS422 with handshake only. Ready Return 9 +V Positive User must supply +12 VDC on this PIN if using Voltage RS232 isolated or +5 VDC if using RS422 isolated configuration.  No connection other- wise. 10 -V Negative User must supply-12 VDC on this PIN if using Voltage RS232C isolated configuration.  No connection otherwise. 11 CTS- CTS Return line for Clear to Send signal (PIN 5) Return used with RS422 with handshake only. 14 TX- Send Data Return line for Send Data signal (PIN 2) Return used with RS422.  Also 20 mA current loop return line for transmit loop. 16 RTS- Request to Return line for Request to Send signal Send Return (PIN 5) used only with RS422 with handshake. 18 RX- Receive Return line for Receive Data signal (PIN 3) Data used with RS422 or 20 mA current loop on Return receive loop.  Internally tied to Signal Ground (PIN 7) for RS232C operations. 20 DTR Data When handshake lines are used, this line is Terminal always active telling the host to send data Ready at any time.  This line is in an undetermined state when handshake is not used. 25 DSR- Data Set Return line used for Data Set Ready signal Read Return (PIN 6) used with RS422 with handshake only. ECLIPSE INSTRUMENTATION DIVISION page 3-1105