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Examples of analog output interconnections
Q+ Q-
Equipment with a current input 2 pieces of equipment with current inputs.
Outputs 1 and 2 serve the purpose of
identifying liquid flow direction.
Multifunctional outputs programmed to identify the liquid flow direction and to negate the flow direction, will
divide the analog output operated in the “Absolute Flow-Rate Value” mode into two outputs, one for each
flow direction.
Equipment with voltage input Current output connected as a voltage
source to feed the (passive) output 2
The output voltage for the equipment to be connected is defined as the voltage drop on resistor R. It holds:
U = I R.
For the voltage range of 0…10V, select R = 500Ω and the analog current output range 0…20mA. Resistor R
shall be placed as close to the input terminals of the equipment as possible. The maximum voltage (voltage
drop on the resistor) is 10V. The input impedance of the controlled equipment shall be at least 100 times
higher than that of resistor R.
The interconnection of the current output as an auxiliary power source for the binary outputs is shown in the
picture above. This arrangement assumes that the current output is not used for the purposes of flow rate
indicator. Here the current output needs to be set in the “Fixed Current” mode of operation. The voltage drop
on resistor Ri is used as supply voltage for the binary output (via resistor Rz). The input impedance of the
equipment shall be at least 10 times higher than that of a resistor Rz, while Rz shall be at least
10 times higher than Ri. It holds: Ri < Rz < input impedance for the equipment to be connected.
Analog output specifications
The analog output signal is controlled by a 12-bit DA converter. The operational range 0 to 20mA is divided
into 4,096 steps. One step (1LSB) corresponds to about 0.005mA (0.025% of 20mA). This resolution applies
to all output ranges. The current range 4 ... 20mA is software-defined with the converter steps reduced
accordingly. The maximum voltage at the current output is 20V; the maximum resistance of the current loop
is therefore 1,000Ω.
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