Notch filter

The EL32xx terminals are equipped with a digital filter. The filter performs a notch filter function and determines the conversion time of the terminal. It is parameterized via the index 0x8000:15. The higher the filter frequency, the faster the conversion time.

Notch filter means that the filter has zeros (notches) in the frequency response at the specified filter frequency and multiples thereof, i.e. it masks these frequencies. In order to filter out 50 Hz, therefore, the 50 or the 10 Hz filter can be used. Since all frequencies lower than the notch frequency usually have to be measured, however, the "50 Hz" setting is to be used in this case.

Notch filter 1: — Typical frequency response of a notch filter set to 50 Hz

	Index 0x80n00:06 The filter function is always active even if the bit is not set, since this is obligatory for the measurement process! The firmware filter can therefore not be switched off.

Details on the conversion time

The conversion time depends on the number of active channels, number of measurements (2/4-wire), filter time, const. computing time
The conversion time for the 2-wire measurement is about twice as long as for the 4-wire measurement
The resistance measurement corresponds to a 4-wire measurement
The process data TxPDO Toggle changes its state if a new measured value is present

	The filter characteristics are set via index 0x8000:15 The filter frequencies are set centrally for all channels of the EL32xx terminals via index 0x8000:15 (channel 1). The corresponding indices 0x8010:15 of the EL3202 or 0x8010:15, 0x8020:15, 0x8030:15 of the EL3204 have no parameterization function.

	Switching off the unused channels of multi-channel terminals Unused channels should be switched off by "not connected" if filter frequencies are ≥ 1 kHz (optimization of conversion times)! The channel concerned is completely disabled and the conversion time of the EL32xx is correspondingly shortened.

By means of a double click on the corresponding object 0x80n0:1A, the respective channels can be switched off in the Set Value Dialog by selecting the "Enum" value "not connected" (see fig. "Set Value Dialog").

	Interference from equipment When operating the fast analog EL320x EtherCAT terminals, high frequency superimposed signals from interfering devices (e.g. proportional valves, stepper motors or DC motor output stages) can be picked up by the terminal. In order to guarantee interference-free operation, we recommend that separate power supply units be used for the terminals and the interference-causing devices. The integrated filter of the terminal (see index 0x80n00:06) should be switched on as an additional measure.

Typical conversion times

EL3201, EL3201-0010, EL3201-0020, EL3201-0030

Filter frequency	Conversion time (update time)
5 Hz	205 ms
10 Hz	105 ms
50 Hz	25 ms
60 Hz	21 ms
100 Hz	15 ms
500 Hz	5 ms
1000 Hz	4 ms
2000 Hz	4 ms
3750 Hz	4 ms
7500 Hz	4 ms
15000 Hz	4 ms
30000 Hz	4 ms
Conversion times in relation to the filter frequencies, 4-wire measurement

EL3202

Filter frequency	Conversion time (update time)
5 Hz	807 ms
10 Hz	410 ms
50 Hz	88 ms
60 Hz	75 ms
100 Hz	46 ms
500 Hz	13 ms
1000 Hz	10 ms
2000 Hz	7 ms
3750 Hz	6 ms
7500 Hz	5 ms
15000 Hz	5 ms
30000 Hz	5 ms
Conversion times in relation to the filter frequencies, 3-wire measurement

EL3202-0010, EL3202-0020, EL3202-0030

Filter frequency	Conversion time (update time)
Filter frequency	4-wire update rate	3-wire update rate
5 Hz	410 ms	610 ms
10 Hz	210 ms	310 ms
50 Hz	47 ms	67 ms
60 Hz	40 ms	57 ms
100 Hz	25 ms	35 ms
500 Hz	7 ms	10 ms
1000 Hz	5 ms	7 ms
2000 Hz	4 ms	5 ms
3750 Hz	4 ms	5 ms
7500 Hz	4 ms	5 ms
15000 Hz	4 ms	5 ms
30000 Hz	4 ms	5 ms

EL3204

Filter frequency	Conversion time (update time)
5 Hz	800 ms
10 Hz	400 ms
50 Hz	82 ms (21 ms / 1 channel)
60 Hz	70 ms
100 Hz	43 ms
500 Hz	11 ms
1000 Hz	7 ms
2000 Hz	6.5 ms (2 ms / 1 channel)
3750 Hz	6 ms
7500 Hz	6 ms
15000 Hz	6 ms
30000 Hz	6 ms
Conversion times in relation to the filter frequencies, 4-wire measurement

EL3208

Filter frequency	Conversion time (update time)
Filter frequency	1 channel active	8 channels active
5 Hz	201 ms	1600 ms
10 Hz	101 ms	807 ms
50 Hz	22 ms	171 ms
60 Hz	18 ms	145 ms
100 Hz	12 ms	92 ms
500 Hz	4 ms	29 ms
1000 Hz	3 ms	20 ms
2000 Hz	3 ms	20 ms
3750 Hz	3 ms	20 ms
7500 Hz	3 ms	20 ms
15000 Hz	3 ms	20 ms
30000 Hz	3 ms	20 ms
Conversion times in relation to the filter frequencies, 2-wire measurement

EL3214 and EL3218

Filter frequency	Conversion time (update time)
Filter frequency	1 channel active	4 channels active
5 Hz	402 ms	1607 ms
10 Hz	203 ms	811 ms
50 Hz	44 ms	175 ms
60 Hz	37 ms	148 ms
100 Hz	24 ms	95 ms
500 Hz	8 ms	32 ms
1000 Hz	6 ms	24 ms
2000 Hz	6 ms	22 ms
3750 Hz	5 ms	21 ms
7500 Hz	5 ms	20 ms
Conversion times in relation to the filter frequencies, 3-wire measurement