Ets Voltage And Current Requirements - Allen-Bradley A-B QUALITY DL20 Series User Manual

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Event Driven Sampling

Event driven sampling uses the edge triggered strobe (ETS) input. Terminal

10 is the ETS - and Terminal 11 is the ETS+ (1.5-15VDC). The DL20 reads

data on the parallel port on either the rising edge or falling edge (one or the

other - not both) as selected in the special functions menu (Set Up I/O Ports).

Data must be present on the parallel data port when the edge occurs. The

data must remain stable for at least 2 milliseconds after the edge occurs. No

more than 50 edges per second should be triggered on the ETS input. Also,

since data is sampled only once with this method, only DC input is

permissible on the parallel input. When using AC modules, we recommend

that data is at the parallel port at least 34 milliseconds before the ETS is

changed.

Note: Strobe line transitions, either from OFF to ON, or from ON to OFF,

should occur in less time than the debounce time for DC sampling or in less

than 1 millisecond for AC sampling.

Important: If AC voltage is used, it could be inadvertently sampled during

the zero crossover of the AC waveform of the Parallel Input Converter

(Catalog No. 2706-NG1, -NG2 Series A or B).

The ETS input (terminal 11) is measured with respect to ETS common

(terminal 10). ETS common is isolated. This input presents a DC load of

470 ohms and 2 diode drops (0.7 Volts per diode).

Terminal 23 (GND) is a ground reference for the data lines D0 through D9,

MS0, MS1, and +5VDC out. If needed, ETS common (terminal 10) can be

externally connected to the ground reference (terminal 23).

Table 7.G shows the voltage and current requirements of the ETS inputs.

Table 7.G