Table of Contents
Advertisement
SDM-SIO1A and SDM-SIO4A Serial Input/Output Modules
2.
Precautions
2
FIGURE 1-2. SDM-SIO4A Serial Input/Output Module
For simplicity, except in sections specific to the SDM-SIO4A, only the
SDM-SIO1A is referred to in the text of this manual. All of the information in
the manual applies to both products unless otherwise noted.
•
WARNING: Ensure that the 12V power supply for the module is switched
off when connecting the power and ground wires to the SDM-SIO1A.
When making connections to a datalogger, always ensure power to the
datalogger is switched off and connect the ground (G) wire first.
WARNING: The RS-485 0V ground reference connection may be needed
•
to ensure all units are referenced to a common ground voltage. This is
more often needed with long cable runs. It is advisable to check the
difference in ground potential with some caution before connecting any
wires, to ensure the potential differences are reasonably small and
excessive current will not flow between the two ground wires. There is a
current limiting resistor fitted in the RG line in the SDM-SIO1A, but this
will not be adequate in the event of a serious ground fault, for example, the
ground references being 240 V apart due to faulty AC wiring. If a large
potential difference is found, please seek the advice of a qualified
electrician before continuing with the installation
CAUTION: The power ground connection to the datalogger should be
•
made with large gauge wire, (for example, 16 AWG or 1.5 mm
provide a low impedance path to ground allowing full protection from
static and electrical transients.
CAUTION: The SDM-SIO1A is considered to be a component of a
•
measurement system that is installed in an enclosure and wired in
accordance with this manual. Due to space considerations, full details of
the maximum ratings of the connections are not given on the device.
Instead the user should study this manual and in particular Section 5.2.2,
Voltage Specifications
(p. 6)
applicable to any terminal before starting an installation.
, to determine the maximum voltages that are
2
) to
Advertisement
Table of Contents
