|
|
EIA-232-E (RS-232)
Function |
|
EIA-530
Function |
PIN #
DB-25 |
TO
DTE |
TO
DCE |
| Shield |
1 |
|
Shield |
1 |
|
|
| Transmit Data (TD) |
2 |
3 |
|
2
14 |
|
>
|
| Receive Data (RD) |
3 |
2 |
|
3
16 |
< |
|
| Request To Send (RTS) |
4 |
7 |
|
4
19 |
|
> |
| Clear To Send (CTS) |
5 |
8 |
|
5
13 |
< |
|
| DCE Ready (DSR) |
6 |
6 |
|
6
22 |
< |
|
| Signal Ground (SG) |
7 |
5 |
|
7 |
|
|
| Received Line Signal Detector (DCD) |
8 |
1 |
| Received Line Signal Detector |
(A) |
| (B) |
|
8
10 |
< |
|
| DTE Ready (DTR) |
20 |
4 |
|
20
23 |
|
> |
| Ring Indicator |
22 |
9 |
N/A |
|
|
----- |
SIGNAL
STATE |
THRESHOLD VOLTAGES |
| Signal with Repsect to SG |
Signal A with Respect to Signal B |
Signal A with Repsect to Signal B |
| RS-232 |
RS-422 |
RS-485 |
| "0", Asserted, ON, Space, Active |
+3 to +25 VDC |
+2 to +6 VDC (Transmitter)
+0.2 to +7 VDC (Receiver) |
+1.5 to +6 VDC (Transmitter)
+0.2 to +12 VDC (Receiver) |
| "1", Disasserted, OFF, Mark, Inactive |
-3 to -25 VDC |
-2 to -6 VDC (Transmitter)
-0.2 to -7 VDC (Receiver) |
-1.5 to -6 VDC (Transmitter)
-0.2 to -7 VDC (Receiver) |
NOTE: Some RS-422 and RS-485 equipment use "+" and "-" descriptors.
The "-" corresponds to "A" and the "+" corresponds to "B". |
| Common AT Port Addresses and Interrupts |
| COM 1 |
3F8h |
IRQ4 |
| COM 2 |
2F8h |
IRQ3 |
| COM 3 |
3E8h |
IRQ4 |
| COM 4 |
2E8h |
IRQ3 |
| LPT1 |
378h |
IRQ7 |
| LPT2 |
278h |
IRQ5 |
| LPT3 |
3BCh |
|
| Floppy Disk |
IRQ6 |
| Real Time Clock |
IRQ8 |
| Re-directed to IRQ2 |
IRQ9 |
| Math Co-processor |
IRQ13 |
| Hard Disk |
IRQ14 |
DECIMAL TO HEX TO ASCII CONVERTER
 
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