Accelnet & Stepnet Plus Panels STO Manual
16-01338 Rev 00
Page 15 of 34
Copley Controls
STO Channel 3 disables the drive (both axes) by disabling both the high and low side MOSFET gate drivers. Any
of the three channels by itself is therefore sufficient to prevent the initiation of motion or halt drive induced
acceleration when the STO function is activated.
Each STO channel receives an input in the form of a voltage (typ24 Vdc to energize and 0V or open to
deenergize) applied to STO_IN1 (+,-) and STO_IN2 (+,-). Note in figure 2 that STO_IN1 (+,-) drives two parallel
connected opto-coupler stages (Channel 1 and Channel 3). STO_IN2 (+.-) drives the opto-coupler stage for
Channel 2 only. Both STO inputs must be simultaneously energized in order for torque/force to be produced. To
achieve the rated SIL and PL capability, both STO inputs must be held simultaneously de-energized by the larger
system when the STO function is activated. In a typical machine application, each STO input is driven by a
+24 Vdc supply voltage switched through a safety relay. Note that the STO inputs are designed to withstand input
voltages to +60 Vdc to provide a measure of overvoltage protection. By definition, the output of an SELV rated
power supply is a maximum of +60 Vdc in a fault condition. Therefore a constraint on the larger system is that the
power supply used to energize the STO inputs must be an SELV type.
7.1 STO Channel Operation
STO Function Active = No force/torque production is possible in motor
STO Function Inactive = Force/torque production in motor is under control of the drive
STO
IN1
STO
IN2
STO Function State
0
0
STO function is active , both inputs de-energized
1
0
STO function is active, one input de-energized
0
1
1
1
STO function is inactive, both inputs energized
The table above shows the operation of the STO channels.
0 = Voltage applied to the STO input is less than or equal to the rated maximum de-energize level.
1 = Voltage applied to the STO input is greater than or equal to the rated minimum energize level.
A motion control system design for Cat. 3 PL d, and/or SIL 3 rating must use 2 channels for the STO function.
Table 7
