Analog Outputs (Bl121 & Bl123) - Hanna Instruments BL120 Instruction Manual

7.6. ANALOG OUTPUTS (BL121 & BL123)
The three 4-20 mA isolated current outputs are factory calibrated and can be configured through the Setup menu as pH / ORP
or Temperature outputs.
Each output can be disabled or configured to a parameter and can be connected to a chart recorder or data logger. The current
signal is proportional to the assigned scale of the assigned parameter (e.g. AO1 - pH, AO2 - ORP, AO3 - Temperature).
To assign the output signal, select the minimum and maximum limit values for the parameter.
The maximum and minimum values for each parameter are defined in the parameter Setup menu.
For example, if the pH was assigned to analog output 1 (AO1) and the minimum and maximum analog output limits are 0
and 14 pH, the entire range will correspond to 4 and 20 mA, respectively (Example 1).
A better resolution of analog output can be obtained if the limits are set, thus limiting the range of interest (Example 2).
The output current is set to 0 mA when the analog output is disabled.
Under range condition generates 4 mA whereas an over range condition generates 20 mA output current value.
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