ADLINK PCI-8154 - Manual (Page 84)

74 Operation Theory
4.4 Mechanical switch interface
We provide some dedicated input pins for mechanical switches
like original switch (ORG), plus and minus end-limit switch (±EL),
slow down switch (SD), positioning start switch (PCS), counter
latch switch (LTC), emergency stop input (EMG) and counter
clear switch (CLR). These switches’ response time is very short,
only a few ASIC clock times. There is no real-time problem when
using these signals. All functions are done by motion ASIC. The
software can just do nothing and only need to wait the results.
4.4.1 Original or home signal
Our controller provides one original or home signal for each axis.
This signal is used for defining zero position of this axis. The logic
of this signal must be set properly before doing home procedure.
Please refer to home mode section for details.
4.4.2 End-Limit switch signal
The end-limit switches are usually installed on both ending sides
of one axis. We must install plus EL at the positive position of the
axis and minus EL at the negative position of the axis. These two
signals are for safety reason. If they are installed reversely, the
protection will be invalid. Once the motor’s moving part touches
one of the end-limit signal, the motion controller will stop sending
pulses and output an ERC signal. It can prevent machine crash
when miss operation.
4.4.3 Slow down switch
The slow down signals are used to force the command pulse to
decelerate to the starting velocity when it is active. This signal is
used to protect a mechanical moving part under high speed move-
ment toward the mechanism’s limit. The SD signal is effective for
both plus and minus directions.