Rockwell Automation 1771-DB Basic Module User Manual - Series A - Manual (Page 26)

Using the Serial Ports
Chapter 4
4–2
CAUTION: Be sure you properly ground the system before
turning on power. A difference in ground potential between the
BASIC Module serial connectors and your program terminal or
other serial device can cause damage to the equipment or loss of
module programs.
Use the following pins for connections made to the program or peripheral
ports. Refer to figure 4.2 for pin descriptions. Not all signals are available
on both ports.
Signal states are:
mark = logical 1 = – voltage
space = logical 0 = + voltage
Pin Name Description
1 1 Chassis/
Shield Connect this pin to chassis ground for shielding purposes.
2 1 TXD TXD is an RS-423A compatible serial output port.
3 1 RXD RXD is an RS-423A compatible serial input data port.
4 RTS RTS is an RS-423 compatible hardware handshaking output line. This line changes to a mark (1) state when the
BASIC Module has data in the output queue and is requesting permission to transmit to the data communications
equipment.
5 CTS CTS is an RS-423A compatible hardware handshaking input line. This line must be in a mark (1) state for the
BASIC Module to transmit on the peripheral port. If no corresponding signal exists on the data communications
equipment, connect CTS to RTS.
6 DSR DSR is a general purpose RS-423A compatible input line. The BASIC Module transmits or receives in the mark (1)
or space (0) state. Use this line for data recorder interface.
7 1 ,9,10 Signal
Common Use the signal common pins to reference all RS-423A/RS-422 compatible signals.
8 DCD If DCD is enabled using CALL 30, the BASIC Module does not transmit or receive characters until the DCD line is
in the mark (1) state. When disabled, the module ignores the state of this line.
11,12,13,15
17,19,21,22
23,24
NC No connection
14,25 422 TXD RS-422A compatible equivalent of the RS-423A TXD line. Differential serial output lines.
16, 18 422 RXD Differential RS-422A compatible serial input lines.
20 DTR DTR is an RS-423A compatible hardware handshaking output line. This line changes to a space (0) state when the
BASIC Module input queue has accumulated more than 223 characters. The DTR line changes to a mark (1) state
when the input queue contains less than 127 characters.
1 program port pins
4.2
Using the BASIC Module
Program and Peripheral
Communication Ports
(continued)
4.2.1
Pin Descriptions