AMCI SV160E2, User Manual, Page: 18 / 120

SV160E2 S
PECIFICATIONS
SV160E2 User Manual
ADVANCED MICRO CONTROLS INC.
18
STO Option
As stated previously, the STO option adds additional circuitry that allows power to be removed from the
power stage of the motor directly. This is a hardware only solution. If either of the two redundant inputs is
inactive, power is removed. This state cannot be overridden by software control.
Inputs 3 and 4 are used as the redundant STO inputs. When an SV160E2 is ordered with the STO functional-
ity, additional components are added to the PC board that directly connects these two inputs to the power
stage of the motor.
An SV160E2-STO reports two additional status bits to the host controller; STO_Active, and STO_Failure.
Basic Functionality

STO_Active:
Normally ‘0’, this bit is set to ‘1’ when power is removed from the motor because one or
both of Inputs 3 and 4 are inactive. This bit resets itself to ‘0’ when both inputs are active.

STO_Failure:
Normally ‘0’, this bit is set to ‘1’ when either or both of Inputs 3 and 4 are inactive, but
the power stage is reporting that it is still active. If this occurs, the SV160E2 will attempt to disable the
power stage through its programming and will refuse to accept move commands. This bit cannot be
cleared by commands from the host controller. It can only be cleared by cycling power to the unit.
Figure R1.3 Basic STO Operation
Additional Functionality
The STO option adds an additional configuration parameter called the Discrepancy Timer Limit. The factory
defaults leave this parameter at 0, which disables the additional functionality. When set to a non-zero value,
the SV160E2-STO performs additional checks to monitor the STO signals for proper operation. The range of
values for the Discrepancy Timer Limit is 0, and 50 to 3,000. The values of 50 to 3,000 represent time in mil-
liseconds.
In normal STO operation, the two redundant inputs change state simultaneously. The inputs being in different
states is an indication of a wiring issue or hardware fault. The Discrepancy Timer Limit parameter sets:

the maximum time that the two inputs can be in different states before the SV160-STO triggers an
STO_Failure non-clearable fault

the minimum time that an input must stay stable between state changes, both active-to-inactive and
inactive-to-active
When recovering from an STO event, if the inputs are active for less than the Discrepancy Timer Limit, the
SV160STO triggers the STO_Failure non-clearable fault.
STOA
STOB
Normal
Operation
Normal
Operation
STO
Cleared
Drive
Re-Enabled
In STO
STO_Active
STO_Failure
Driver_Fault
Drive_Enabled
Enable_Drive
Inputs
Cmd
Sta
tu
s
Drive Enabled on
0 1 transition of
the Enable_Drive bit.
