A01251 — CU: CU-EEPROM incorrect read-write data

A01251 is raised by the Control Unit (CU) when it registers an error while reading the read-write data of its EEPROM (CU-EEPROM). The alarm concerns all drive objects. It travels with an alarm value held in r2124, which is read as a decimal number; the manual decodes no individual values and states that this value is Only for internal Siemens troubleshooting. Which remedy applies depends on whether the value in r2124 is below 256 or 256 and above.

• The Control Unit has detected an error while reading the read-write data of its EEPROM; this is the only cause the manuals give for this alarm.

1. Read the alarm value in r2124 and interpret it as a decimal number — the manuals note that this value serves only for internal Siemens troubleshooting.
2. Value below 256: carry out a POWER ON (switch the power off and on again). If the alarm still comes back, replace the Control Unit.
3. Value 256 or above: clear the fault memory of the drive object that raised this alarm (p0952 = 0). Alternatively, clear the fault memory of all drive objects in one step (p2147 = 1); this alternative is printed for G130, G150, S120 and S150. If the alarm still comes back, replace the Control Unit.

• The drive stores the alarm value belonging to this alarm in r2124; interpret the value as a decimal number.
• No decoding of individual values is printed — the value is stated to serve only for internal Siemens troubleshooting.

• r2124 — alarm value: read it as a decimal number to decide between the two remedy branches (below 256, or 256 and above).
• p0952 — set to 0 to clear the fault memory of the drive object that raised this alarm; applies when the value in r2124 is 256 or above.
• p2147 — set to 1 to clear the fault buffer of all drive objects at once, as the alternative to p0952; given in the manuals for G130, G150, S120 and S150.

This alarm needs no separate acknowledgement: it is cleared by the remedy itself — a POWER ON when the value in r2124 is below 256, or clearing the fault memory when it is 256 or above. If the alarm keeps returning after that, the Control Unit must be replaced.