What it means
During power-up the Control Unit performs an automatic internal self test. This test cannot be completed while the pulses are not enabled, so the power-up is stopped — the drive reports the condition as SI: Power up stopped due to STO via terminals
. The manual points to one situation in which this happens: the 'STO via terminals at the Power Module' function may be in use, with STO selected in at least one hardware switch-off signal path at the Power Module. STO stands for Safe Torque Off.
Why it appears
- The automatic internal self test of the Control Unit could not be completed during power-up because the pulses were not enabled.
- The 'STO via terminals at the Power Module' function may be in use, and STO is selected in at least one hardware switch-off signal path at the Power Module.
What to check
- Deselect STO:
Deselect STO via the STO terminals at the Power Module (connect STO_A and STO_B to 24 V).
- If the 'STO via terminals at the Power Module' function is not required, deactivate it via the DIP switch: set both DIP switches to OFF.
Acknowledging and restarting
Once the cause has been removed, the Control Unit continues to power up; the alarm itself requires no acknowledgement action. While the alarm remains, a possibly existing brake is kept closed.
The same on every family
Every manual that describes A01790 gives it the same reaction, acknowledgement and message class.
| Drive family | Reaction | Acknowledge | Message class | Component | Manual |
|---|---|---|---|---|---|
| G120 | NONE | NONE | Safety monitoring channel has identified an error (10) | — | SINAMICS G120 · p. 859 |
The drives this code lives on
A01790 is described for G120. These are the converters of those families in our catalogue — price on request.
Questions technicians ask
What does alarm A01790 mean on a SINAMICS G120?
The Control Unit could not complete its automatic internal self test during power-up because the pulses were not enabled, so the power-up is stopped. The manual points to the 'STO via terminals at the Power Module' function with STO selected in at least one hardware switch-off signal path.
How do I clear A01790?
Deselect STO by connecting STO_A and STO_B to 24 V at the STO terminals of the Power Module, or deactivate the 'STO via terminals at the Power Module' function by setting both DIP switches to OFF. After the cause has been removed, the Control Unit continues its power-up.
Does A01790 have to be acknowledged?
No separate acknowledgement action is needed. Once the cause has been removed, the Control Unit continues to power up by itself.
Why is the brake closed while A01790 is active?
The manual notes that while the alarm remains, a possibly existing brake is kept closed.
Codes next to this one
Source
Written from Siemens' own List Manuals and operating instructions; every number, designation and parameter on this page is checked against them before publication.
All SINAMICS codes: fault and alarm codes · the A01xxx group · SINAMICS manuals · Siemens manuals