6-9 Safe Torque Off 
AC30V series Variable Speed Drive 
STO Technical Specification 
INPUTS SPECIFICATION 
STO A Input and STO B Input comply with IEC61131-2. Note: inputs do not have hysteresis. 
 
Recommended input voltage for low level:  0V to +5V 
Recommended input voltage for high level:  +21.6V to +26.4V 
Typical input threshold voltage:  +10.5V 
Indeterminate input range:  +5V to +15V. Function is undefined. 
Absolute maximum input voltage:  -30V to +30V 
Typical input current @ 24V  9mA 
Fault detection time
4
:  2.3sec typical; 
  < 1.6sec will not generate a fault 
  > 3.0sec will generate a fault. 
Response time
5
  > 2ms 
  6ms typical 
  < 10ms 
Conditions in which the STO inputs are operative:  All, i.e. STO cannot be disabled in any condition 
 
  
4
 A fault is defined in this context as STO A Input and STO B Input being sensed in opposite logic states. 
5
 Response time is the time from the first STO input becoming active (voltage level is low) until torque production has ceased