Typical power consumption SGR-V for maximum output (1 V)
5 VDC
50 mW
(approx. 10.0 mA)
12 VDC
55 mW
(approx. 4.5 mA)
24 VDC
60 mW
(approx. 2.5 mA)
.
Maximum power consumption 65 mW at the highest input voltage.
Maximum input current 12.5 mA at the lowest input voltage.
Maximum inrush current 200 mA.
Typical power consumption SGR-A for max output (20 mA)
5 VDC
77 mW
(approx. 28 mA with 100 Ω load resistor)
12 VDC
83 mW
(approx. 24 mA with 100 Ω load resistor)
24 VDC
100 mW
(approx. 6 mA with 100 Ω load resistor)
The above mW values represent the dissipation within the SGR-A. For the total power the energy in the load resistor has to
be added.
For supply voltages below 12 Volts or above 20 Volts it is advised to use a load resistor of less than 500 Ω to keep the power
consumption as low as possible.
2.3.2 Data connection
Connection to a Personal Computer by Universal Serial Bus (USB)
The connection depends on the use of a RS-485 to USB converter.
The converter
must have galvanic isolation between the inputs and outputs to prevent possible damage to the SGR
digital interface. This is particularly an issue with portable computers (laptops, etc.) in which the power supplies
can generate large voltage spikes.
A suitable converter is the model USOPTL4 from B & B Electronics. One end has the USB connector to the PC the other end has
a connector with screw terminals for the instrument wires. This RS-485 converter is powered from the USB interface, so no
additional power adaptor is necessary.
*Note
Switches on the converter should be set for RS-485, 2-wire operation and Echo off.
Shield - ground connection
SGR connections to USB
USB to PC
Not connected
Analogue out +
Analogue out -
Modbus® RS-485
Modbus® RS-485
Modbus® common / Ground
Power 5 to 30 VDC
Power ground / RS-485 common
+ V
- V
RS-485 / USB converter
Common
*
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