F01221 — CU: Bas clk cyc too low

F01221 means that the closed-loop control / monitoring in the CU cannot maintain the envisaged clock cycle: the runtime of the control/monitoring is too long for the clock cycle that has been set, or the computing time remaining in the system is not sufficient for it. The remedy in every case is to increase the basic clock cycle of the DRIVE-CLiQ communication.

• The runtime of the closed-loop control / monitoring is too long for the particular clock cycle that has been set.
• The computing time remaining in the system is not sufficient for the closed-loop control / monitoring.

1. Note that the fault value (r0949, to be interpreted hexadecimal) gives no on-site diagnostic pointer — the manuals state it is Only for internal Siemens troubleshooting.
2. Increase the basic clock cycle of the DRIVE-CLiQ communication. The sampling times are pre-set in p0112 (t_sample for p0115); p0115 is the sampling time for the supplementary functions that results from this pre-setting.

• The drive writes the fault value to r0949; the message value (%1) shows this value, and it is to be interpreted hexadecimal.
• The manuals print no decoding of the value for this code: it is Only for internal Siemens troubleshooting.

• p0112 — sampling times pre-setting (t_sample for p0115); this is the parameter the remedy refers to when the basic clock cycle of the DRIVE-CLiQ communication has to be increased.
• p0115 — sampling time for the supplementary functions (t_samp suppl_fct); its value is pre-set via p0112, where the clock-cycle change for this fault is made.
• r0949 — fault value; for F01221 it holds the value shown as the message value, read hexadecimal, and is reserved for internal Siemens troubleshooting.

The fault is acknowledged immediately: after increasing the basic clock cycle of the DRIVE-CLiQ communication (sampling-times pre-setting p0112), acknowledge the message at the operator panel or in the commissioning tool. The drive does not perform an automatic protective reaction of its own to this fault; once the clock-cycle setting has been corrected, acknowledging the message clears it.