Data Connection - Kipp & Zonen SMP series Instruction Manual

Typical power consumption SMP-V for maximum output (1 V)
5 VDC 50 mW
12 VDC 55 mW
24 VDC 60 mW
.
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 SMP-A for max output (20 mA)
5 VDC 77 mW
12 VDC 83 mW
24 VDC 100 mW
The above mW values represent the dissipation within the SMP-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.

2.9.2 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 SMP
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.
SMP connections to USB
Shield - ground connection
*Note Switches on the converter should be set for RS-485, 2-wire operation and Echo o .
(approx. 10.0 mA)
(approx. 4.5 mA)
(approx. 2.5 mA)
(approx. 28 mA with 100 Ω load resistor)
(approx. 24 mA with 100 Ω load resistor)
(approx. 6 mA with 100 Ω load resistor)
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
RS-485 / USB converter
Common
+ V
- V
19
USB to PC
*