Teledyne 300E - DTE Versus DCE Communication; Table 6-14: COM-A and COM-B Default Pin Assignments

Model 300E Carbon Monoxide Analyzer
Instruction Manual
Operating Instructions
P/N 04288 REV: A 91
Table 6–14: COM-A and COM-B Default Pin Assignments
PIN # COM-A (RS-232) COM-B (RS-485) COM-B (RS-232)
1 Not Used Not Used Not Used
2 TRANSMIT DATA* DATA+ TRANSMIT DATA
3 RECEIVE DATA* DATA- RECEIVE DATA
4 Not Used Not Used Not Used
5 SIGNAL GROUND SIGNAL GROUND SIGNAL GROUND
6 Not Used Not Used Not Used
7 DATA SET READY* Not Used DATA SET READY
8 REQUEST TO SEND*
(=DTE Ready)
Not Used REQUEST TO SEND
9 Not Used Not Used Not Used
* Switchable for COM-A at Rear
Panel using the DTE-DCE switch
6.8.4. DTE versus DCE Communication
RS-232 was developed for allowing communications between Data Terminal
Equipment (DTE) and Data Communication Equipment (DCE). Dumb Terminals
always fall into the DTE category while modems are always considered DCE’s. The
difference between the two is which pin is assigned the Data Receive function that
is assigned the Data Transmit function. DTE’s receive data on pin 2 and transmit
data on pin 3. DCE’s receive data on pin 3 and transmit data on pin 2.
To allow the analyzer to be used as either a DTE or DCE without the need for a
special adapter, there is a switch located just below the connector for COM-A that
switches COM-A between DTE and DCE.
5
4
3
2
1
9
8
7
6
1
2
*
3
* 4
5
6
7 8
9