Campbell Scientific SDM-SIO1 Serial Input/Output Module - Manual (Page 13)

SDM-SIO1 Serial Input/Output Module
TABLE 3-2. SDM-SIO1 Connections (left to right as viewed from the front of the unit)
SDM Power Connections RS-232 Connections RS-485/RS-422
C1 C2 C3 G +12 V G RX-A CTS-B RTS-Y TX-Z 0 V Z Y B A
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
15 14 13 12 10 9 8 7
Note: Italic numbers indicate which pins are connected internally (for use with RS-485 termination resistors etc.).
For example the signals present on pin 7 will also be present on pin 15.
TABLE 3-3. SDM-SIO1 Functional Description of the Connections
Case Text Description
1 C1 SDM data enable line – connect to datalogger SDM C1
2 C2 SDM clock line – connect to datalogger SDM C2
3 C3 SDM data line – connect to datalogger SDM C3
4 G Connect to the datalogger power ground (G) (1)
5 +12 V Main power supply – connect to logger 12 V
6 G RS-232 0 V reference/second G connection (2)
7 RX-A RS-232 receive line
8 CTS-B RS-232 CTS hardware handshaking line / output
9 RTS-Y RS-232 RTS hardware handshaking / input
10 TX-Z RS-232 transmit line
11 0 V RS-485 0V reference line (3)
12 Z ‘–’ RS-485 output line, line Z
13 Y ‘+’ RS-485 output line, line Y
14 B ‘–’ RS-485 input line, line B
15 A ‘+’ RS-485 input line, line A
(1) At least one of the two G terminals (‘G’) must be connected to the logger’s
ground terminal or earth boss.
The ground connection to the datalogger should be made
with large gauge wire, e.g. 16/0.2 to provide a low
impedance path to ground to allow full protection from
static and electrical transients. CAUTION
(2) The ‘G’ (pin 6) can be used for the RS-232 zero volt reference or any other
ground connection needed, e.g. shields.
(3) There is a 100R resistor in series with the datalogger’s ground connection.
This connection should be used when connecting RS-485 equipment by long
wire lengths. It insures both systems have a common ground reference point.
See Section 3.2, Safety Considerations, before connecting.
7