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 drive to produce motion. Each STO input is opto-isolated and accepts 24 V levels directly without
the need for external current limiting resistors.
IMPORTANT
: The drive 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 drive.
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 2-22:
STO Connector Pinout
Pin # Signal
Description
In/Out/Bi
Connector
1
Power
Use only to defeat STO by connecting to STO
1 IN and STO 2 IN. Not for customer use.
Output
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 -
Use only to defeat STO by connecting to
RETURN. Not for customer use.
Output
Table 2-23:
STO Mating Connector Ratings
Type
5-Pin Terminal Block
Aerotech Part Number
ECK02393
Manufacturer Part Number
(1)
Phoenix 1827622
Insulation Strip Length
7 mm (1/4 in)
Tightening Torque
0.22..0.25 N·m
One conductor stranded with ferrule and
plastic sleeve
18..22 AWG (0.25..0.75 mm
2
)
Two conductors with the same cross-
section, stranded, twin ferrule with plastic
sleeve
20 AWG (0.5 mm
2
)
(1) Refer to the manufacturer website for additional information.
2.4. Safe Torque Off Input (STO)
iXC6e/XC6e Hardware Manual
50
www.aerotech.com
