What it means
The manuals title this alarm "CAN: Number of mapped bytes exceeded". It is raised when the objects mapped into the CAN telegram together occupy more bytes than the telegram size for net data provides — a maximum of 8 bytes is permissible. Because the cause lies in the mapping, the remedy is applied in the CAN mapping parameters listed below.
Why it appears
- The objects mapped into the CAN telegram need more bytes in total than the telegram size for net data provides — a maximum of 8 bytes is permissible.
What to check
- Go through the CAN mapping parameters: the receive side is mapped with p8710 (RPDO 1) to p8717 (RPDO 8), the transmit side with p8730 (TPDO 1) to p8737 (TPDO 8).
- Map fewer objects or objects with a smaller data type until the total number of mapped bytes stays within the permissible 8 bytes.
Parameters the manual names
- p8710 — CAN Receive Mapping for RPDO 1: check the objects mapped here when shortening the receive mapping.
- p8711 — CAN Receive Mapping for RPDO 2: check the objects mapped here when shortening the receive mapping.
- p8712 — CAN Receive Mapping for RPDO 3: check the objects mapped here when shortening the receive mapping.
- p8713 — CAN Receive Mapping for RPDO 4: check the objects mapped here when shortening the receive mapping.
- p8714 — CAN Receive Mapping for RPDO 5: check the objects mapped here when shortening the receive mapping.
- p8715 — CAN Receive Mapping for RPDO 6: check the objects mapped here when shortening the receive mapping.
- p8716 — CAN Receive Mapping for RPDO 7: check the objects mapped here when shortening the receive mapping.
- p8717 — CAN Receive Mapping for RPDO 8: check the objects mapped here when shortening the receive mapping.
- p8730 — CAN Transmit Mapping for TPDO 1: check the objects mapped here when shortening the transmit mapping.
- p8731 — CAN Transmit Mapping for TPDO 2: check the objects mapped here when shortening the transmit mapping.
- p8732 — CAN Transmit Mapping for TPDO 3: check the objects mapped here when shortening the transmit mapping.
- p8733 — CAN Transmit Mapping for TPDO 4: check the objects mapped here when shortening the transmit mapping.
- p8734 — CAN Transmit Mapping for TPDO 5: check the objects mapped here when shortening the transmit mapping.
- p8735 — CAN Transmit Mapping for TPDO 6: check the objects mapped here when shortening the transmit mapping.
- p8736 — CAN Transmit Mapping for TPDO 7: check the objects mapped here when shortening the transmit mapping.
- p8737 — CAN Transmit Mapping for TPDO 8: check the objects mapped here when shortening the transmit mapping.
Acknowledging and restarting
No acknowledgement is required. The alarm is remedied at the mapping itself: once fewer objects or objects with a smaller data type are mapped and the total stays within the 8 bytes the telegram for net data provides, the condition behind A08756 is gone.
What differs between the drive families
Straight from the manuals' own fields — A08756 is not described identically everywhere.
| Drive family | Reaction | Acknowledge | Message class | Component | Manual |
|---|---|---|---|---|---|
| S120, S150 | NONE | — | Error in the parameterization / configuration / commissioning procedure (18) | None | SINAMICS S120, S150 List Manual · p. 2928 |
| G130, G150 | NONE | NONE | Error in the parameterization / configuration / commissioning procedure (18) | None | SINAMICS G130, G150 List Manual · p. 1642 |
| G120 | NONE | NONE | Error in the parameterization / configuration / commissioning procedure (18) | — | SINAMICS G120 · p. 901 |
The drives this code lives on
A08756 is described for G120, G130, G150, S120, S150. These are the converters of those families in our catalogue — price on request.
Questions technicians ask
What does alarm A08756 mean on a SINAMICS drive?
It reports that the objects mapped into the CAN telegram together exceed the telegram size for net data; a maximum of 8 bytes is permissible.
How do I fix A08756?
Map fewer objects or objects with a smaller data type. The mapping is set with p8710 to p8717 (receive, RPDO 1 to RPDO 8) and p8730 to p8737 (transmit, TPDO 1 to TPDO 8).
Does A08756 have to be acknowledged?
No. The condition is removed by correcting the CAN mapping itself; no acknowledgement action is needed.
How many mapped bytes does a SINAMICS CAN telegram allow?
8 bytes. Mapping more than that raises A08756.
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 A08xxx group · SINAMICS manuals · Siemens manuals