Campbell SDM-SIO2R, Руководство по эксплуатации продукта

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Table 6-6: SDM-SIO2R functional description of sensor connections
Pin
Case text
(RS-232
Function)
RS-485
Function
Connection to Description
3 G
DC ground from power
supply
4 12V
DC voltage source from
power supply
1
Connection RG has a 100 Ω resistor in series with the data logger ground connection. This connection should be
used when connecting RS-485 equipment by long wire lengths. It ensures both systems have a common ground
reference point. See
Precautions (p. 1) before connecting.
2
The GND can be used for the RS-232 zero volt reference or any other ground connection needed, for example,
shields.
The connection of the wires to the remote serial device or sensor will vary with type of device and
method of communication. It is necessary to work out the best mode of operation of the serial
device, taking into consideration issues such as power consumption, cable lengths (RS-485 being
better than RS-232 for long cables), synchronization of data collection, etc.
NOTE:
If possible, use screened cable for connecting the SDM-SIO2R to remote sensors or devices.
Check the manual of the device for details on where to connect the screen for maximum
effectiveness.
RS-422 mode is functionally the same as RS-485 mode except the connection is limited to a
point-to-point system. Connections and programming for
RS-422 are otherwise identical to full-duplex RS-485.
When operating in RS-232 mode, the SDM-SIO2R also supports hardware handshaking.
Wiring examples for connecting the SDM-SIO2R (p. 21) provides examples of different
connection schemes for the serial devices. Further discussion of different modes of operation is
given in
Operation (p. 34).
6.2.1 Power connections and current limits
SDM-SIO2R power connections and current limits are shown in the following subsections.
SDM-SIO2R Serial Input/Output Module with Switched Sensor Power 19