ADLINK PCI-8164 - Manual (Page 124)

112 Operation Theory
4.3 The limit switch interface and I/O status
In this section, the following I/O signal operations are described.
X SD/PCS: Ramping Down and Position Change sensor
X
±
EL: End-limit sensor
X
ORG: Origin position
In any operation mode, if an
±
EL signal is active during any mov-
ing condition, it causes the 8164 to stop automatically outputting
pulses. If an SD signal is active during moving conditions, it
causes the 8164 to decelerate. If operating in a multi-axis mode, it
automatically applies to all related axes.
4.3.1 SD/PCS
SD/PCS signal pins are available for each axis and acts as the
input channel. It can be connected to a SD (Slow Down) or Posi-
tion Change Signal (PCS). To configure the input signal type use
the function _8164_set_sd_pin().
When the SD/PCS pin is directed to a SD (the default setting), the
PCS signal is kept at a low level and vice versa. Care must be
taken with the logic attributes of the signal not being used.
The slow-down signals are used to force the output pulse (OUT
and DIR) to decelerate to and then maintain the StrVel when it is
active. The StrVel is usually smaller than MaxVel. This signal is
useful in protecting a mechanism moving under high speeds
toward the mechanism’s limit. SD signal is effective for both plus
and minus directions.
The ramping-down function can be enabled or disabled using the
software function _8164_set_sd(). The input logic polarity, level
operation mode, or latched input mode can also be set by this
function. The signal status can be monitored using
_8164_get_io_status().