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4.2 Switching function (only for 3-wire operation)
OUTx changes its switching status if it is above or below the set switching limits
(SPx, rPx). The following switching functions can be selected:
• Hysteresis function / normally open: [OUx] = [Hno] (→ fig. 1).
• Hysteresis function / normally closed: [OUx] = [Hnc] (→
First the set point (SPx) is set, then the reset point (rPx) with the requested
difference.
• Window function / normally open: [OUx] = [Fno] (→ fig. 2).
• Window function / normally closed: [OUx] = [Fnc] (→
The width of the window can be set by means of the difference between SPx
and rPx. SPx = upper value, rPx = lower value.
1 2
P = system pressure; HY = hysteresis; FE = window
4.3 Analogue function
The analogue output can be configured.
• [OU2] defines whether the set measuring range is provided as 4...20 mA
([OU2] = [I]) or as 20...4 mA ([OU2] = [InEG]).
Scaling can be set by means of the teaching process or by entering a value for the
ASP and AEP parameters.
• Teaching the analogue start point [tASP] or setting the parameter [ASP] defines
at which measured value the analogue signal is 4 mA (20 mA at [InEG]).
• Teaching the analogue end point [tAEP] or setting the parameter [AEP] defines
at which measured value the output signal is 20 mA (4 mA at [InEG]).
Minimum distance between [ASP] and [AEP] = 25 % of the final value of the
measuring range (turn-down 1:4); for PI2899: 25 % of the measuring span.
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