User Guide
13
3.3.7 Connecting a 9 way socket to the SDM-SIO1
Notes:
The CTS-B (CTS) and RTS-Y (RTS) lines can also be used to trigger
external circuitry if desired when not being used in handshaking mode.
Note that when using CTS-B and RTS-Y lines as input and output that the
voltage levels are +/-12V NOT 0 and 5V.
CTS-B and RTS-Y can’t be used as separate input and outputs when in
RS-485 mode.
.
3.4 Power conservation
The SDM-SIO1 features an industry standard RS-232/RS-485 driver chipset
(Maxim 3160) which ensures maximum likelihood of compatibility with all other
devices. When the driver is powered on it uses more power than one of the
datalogger’s control port based “com ports” – typically 6 mA minimum, partly
because it generates the correct signal levels which in itself requires power and
partly because, in the case of RS-232 signals, the resting state of ~-6V driving a
nominal RS-232 ~3k load implicitly wastes ~2 mA of current per line.
0V
RS-232 RTS
RS-232 RX
RS-232_TX
RS-232 CTS
To logger
Pin 5
Pin 7
Pin 2
Pin 3
Pin 8
RS-232 9 way D
- type connector
connector
1)
Note this diagram is for adding a 9 way D - type plug to the SDM -
SIO1. A standard one to one serial lead can then be used to
connect to another piece of equipment ( e.g . a PC or sensor)
2)
Since there is no standard that indicates whet her certain devices
should be DTE or DCE it may be necessary to reverse the CTS
- B
and RTS - Y pins when wiring hardware handshaking. You may
may
cross the wires either by crossing them manually (as shown by
by
dotted lines) or, by purchasing a special cable for this purpose.
DTE configuration
Note 2
C1
C2
C3
G
+12V
G
RX - A
CTS - B
RTS - Y
TX - Z
0V
Z
Y
B
A
1
2
3
4
5
6
7
8
9
10
- Z
11
12
13
14
15
