1
SDM-CVO4 4-Channel Current/Voltage
Output Module
1. Introduction
The SDM-CVO4 is attached to a data logger and outputs variable voltage or
current signals under data logger program control. Typical applications include
driving remote current-loop display units, retransmitting measured values to
industrial control systems, sending control signals to valve controllers, and
providing excitation voltages or currents to external sensors.
This manual provides information only for CRBasic data loggers.
For retired Edlog data logger support, see an older manual at
www.campbellsci.com/old-manuals
2. Precautions
The potential voltage difference between the data logger and the SDM-CVO4
outputs is considered to be non-hazardous (less than 50 V). Therefore, the
SDM-CVO4 is not a safety risk to the user.
As with the data logger, ensure that the device has a good connection to an
earth grounding point to allow the safe discharge of transient voltages and also
ensure proper screening of the device. The SDM-CVO4 has two
G
terminals
on the black connector used for data logger connections. Use one of these
grounds to connect the device directly to the enclosure ground lug to ensure the
lowest resistance path to ground.
When the SDM-CVO4 is used in applications where the potential difference
between the data logger and the output terminals exceeds 50 V RMS AC,
74 VDC, careful consideration has to be taken to ensure safe operation and
compliance with local safety regulations. For such applications Campbell
Scientific does not supply the device as a stand-alone device which will meet
all safety requirements. The SDM-CVO4 is supplied as a component for the
user to install in a system that is, itself, designed to comply with such
regulations. The following guidance is given to help users meet the
requirements of such regulations.
The SDM-CVO4 is designed such that the internal safety barrier meets the
requirements of BS EN 61010-1 (similar to IEC 950). However, the method of
wire connection and earthing facilities prevents the unit being claimed as
compliant with such standards, when supplied as a stand-alone unit.
To meet the safety requirements of most countries, wires carrying hazardous
voltages, terminated in screw terminals must be housed in an enclosure
requiring a tool to open it, and the enclosure must have international symbols
on the outside warning of high voltages. An additional warning label, in the
local language, may be required stating that the source of hazardous voltage
must be turned off before the enclosure is opened.
NOTE
