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The comms connector is a standard DB9. It provides an RS232 compatible interface. It is used for communications with a PC for programming and use with SPLatLink.
The RS232 interface is a basic interface with transmit data, receive data and ground. Pinouts are as follows:
Pin |
Signal name |
Comments |
1 |
|
Not connected |
2 |
RxD |
Serial data output from board |
3 |
TxD |
Serial data input to board |
4 |
|
Not connected |
5 |
Gnd |
0V, signal ground |
6 |
DSR |
Data Set Ready, switchable output line. |
7 |
|
Not connected |
8 |
CTS |
Hard-wired to +5V for accessory power |
9 |
|
Not connected |
This is a DCE ("looks like a modem") interface, suitable for connection to a DTE, such as a computer, with a straight-through cable.
To connect the SPLat to another DCE, like a modem, you must use a crossover cable. The cable will need the following wiring:
SPLat pin |
Modem pin |
1 |
|
2 RxD |
3 TxD |
3 TxD |
2 RxD |
4 |
|
5 Gnd |
5 Gnd |
6 DSR |
7 RTS |
7 |
|
8 CTS |
4 DTR |
9 |
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Built in multi-drop capability
The interface has a special design that allows several boards' interfaces to be connected in parallel, like pin to like pin. This makes possible small systems of up to 5 boards in a multi-drop communications configuration, connected perhaps to a shared modem. Please contact SPLat Controls for information about suitable firmware to support this arrangement.
See also RS232 pinouts: A primer
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