Aerotech Automation1 XC2, Hardware Manual, Page: 53 / 96

2.4. Safe Torque Off Input (STO)
The STO circuit is comprised of two identical channels, each of which must be energized in order for the
XC2 to produce motion. Each STO input is opto-isolated and accepts 24V levels directly without the need
for external current limiting resistors.
IMPORTANT : The XC2 might be equipped with an STO bypass circuit board. The bypass
circuit board defeats the STO safety circuit and allows the system to run at all times. To use
the STO safety functionality, remove the circuit board and make connections as outlined in
this section.
IMPORTANT : The application circuit and its suitability for the desired safety level is the
sole responsibility of the user of the XC2.
WARNING : STO wires must be insulated to prevent short circuits between connector pins.
The primary concern is a short circuit between STO 1 IN and STO 2 IN wire strands.
Table 2-23: STO Connector Pinout
Pin # Signal Description In/Out/Bi Connector
1 Power
Used to defeat STO by connecting to STO 1 IN
and STO 2 IN
N/A
2 STO 1 IN STO Channel 1 Positive Input Input
3 RETURN STO Negative Input Input
4 STO 2 IN STO Channel 2 Positive Input Input
5 Power Supply - Used to defeat STO by connecting to RETURN N/A
Table 2-24: Mating Connector Part Numbers for the STO Connector
Description
Aerotech
P/N
Phoenix
P/N
Tightening
Torque
(Nm)
Wire Size:
AWG [mm
2
]
5-Pin Terminal Block ECK02393 1827622 0.22 - 0.25 2.5 - 0.05 [14-30]
XC2 Hardware Manual 2.4. Safe Torque Off Input (STO)
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