RS-232 Serial Data Communications

Transcription

1 CAT Paper: P- RS- Serial Data Page Some of the CAT controllers have RS- port capability to enable communications between the controller and a personal computer. This paper will address the RS- interface signals, how these signals are applied to the CAT controllers, and interconnection diagrams. A Look At The RS- Signals The RS- standard (EIA/TAI--E) specifies a high level signal output as being between + to + volts and a low level as being between - and - volts. Below is an illustration of those logic levels as defined by the RS- standard. Space +V To +V 0V RS- Logic Specifications Mark -V To -V A low level (-V to -V) is defined as a logic and is referred to as marking. A high level (+V to +V) is defined as a logic 0 and is referred to as spacing. RS- Signals Identification The RS- standard breaks down the various signals into four catagories; data, control, timing, and common. These signals, listed and identified on the following page, are very numerious and most applications do need most if not all of the signal connections. The CAT controllers only need a few of these signals because the data protocol used requires no signal handshaking. (9) 9-

2 CAT Paper: P- RS- Serial Data Page Protective Signal Reserved 9 Reserved 0 Unassigned Secondary DCD Secondary CTS Secondary TD Transmit Clock Secondary RD Receiver Clock Local Loopback 9 Secondary RTS 0 Remote Loopback Ring Indicator (RI) Data Rate Detect Transmit Clock Test Mode PC Computer RS- Connector Pin Assignment, Pin Connector 9 Ring Indicator (RI) PC Computer RS- Connector Pin Assignment, 9 Pin Connector (9) 9-

3 CAT Paper: P- RS- Serial Data Page Signal connections for the CAT controllers require only three signal lines; transmit data, receive data, and ground. Since some computer serial ports and/or serial communications software are setup to interface with the RTS (Request To Send) and CTS (Clear To Send), it becomes necessary to satisfy these signal requirements before data transmission can take place. The diagrams below illustrate connections necessary for both the CAT-000 and the CAT-00DX controller s RS- port. Note that the CAT-000 has two RS- interface plugs and cable connections are illustrated for both types. CAT-000 RS- Interface Cables Protection Signal Protection Signal Computer RS- Port DB- Connector 0 Computer RS- Port DB- Connector 0 CAT-000 J CAT-000 J0 Note: On the CAT-000 PC board, Pins and of jumper J must be jumpered. (9) 9-

4 CAT Paper: P- RS- Serial Data Page Computer RS- Port DB-9 Connector Computer RS- Port DB-9 Connector CAT-000 J CAT-000 J0 Note: On the CAT-000 PC board, Pins and of jumper J must be jumpered. CAT-000 Communication Parameters Whenever you communicate with the CAT-000 through a direct connection cable, the microprocessor serial communications port is preset as follows: Baud 00 Data Bits Stop Bits Parity None (9) 9-

5 CAT Paper: P- RS- Serial Data Page CAT-00 and the CI-00 Interface RS- interfacing with the CAT-00 controller requires the CI-00 interface module. This module is necessary to performs the necessary data level conversions because the CAT-00 controller uses TTL level (0V/V) RS- signal levels. J J J CAT-00DX Repeater Controller J J CI-00 J CAT-00 Communication Parameters Whenever you communicate with the CAT-00 through the CI-00 interface module, the microprocessor is configured as follows: Baud 00 Data Bits Stop Bits Parity None (9) 9-

6 CAT Paper: P- RS- Serial Data Page CAT-00 RS- Interface Cables Computer RS- Port DB- Connector CI-00 DB- Connector Protection Signal 0 Protective Signal Computer RS- Port DB-9 Connector CI-00 DB- Connector Protective Signal (9) 9-