Description Of The Ep1908 Test Pulses - Beckhoff EP1908 Operating Instructions Manual

Route the signal cable separately
The signal cable must be routed separately from potential sources of interference, such as motor supply
cables, 230 V power cables etc.!
AC
Interference caused by cables routed in parallel can influence the signal form of the test pulses and thus
cause diagnostic messages (e.g. sensor errors or OpenLoad errors).
D: Distance between the cable ducts should be as large as possible
blue arrows: signal line
red arrows: potential source of interference
The common routing of signals together with other clocked signals in a common cable also reduces the
maximum propagation, since crosstalk of the signals can occur over long cable lengths and cause diagnostic
messages.
The test pulses can be switched off (sensor test parameter) if the connection of a common cable is
unavoidable. However, this then leads to a reduction in the degree of diagnostic cover when calculating the
performance level.
5.2.7

Description of the EP1908 test pulses

The typical length of a test pulse (switching from 24 V to 0 V and back to 24 V) is 350 µs and takes place
approx. 180 times per second.
The test pulses at the outputs Pulse Output 1 to Pulse Output 8 are generated separately for each channel in
order to be able to detect cross-circuits between the individual channels of a terminal and also between
channels of different terminals. In order to generate test pulses as shown in the diagram, the Sensor test
active safety parameter must be set to true for the respective channels. The test cycle for all 8 channels is
typically 5.5 ms. The times between the test pulses of different channels vary, thus allowing better diagnostic
detection.
EP1908
NOTE
Version: 3.0.0
Operation
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