A32418 — Encoder 2: Speed change not plausible (alarm)

A32418 is the Encoder 2 alarm for a speed change the drive judges as not plausible: for an HTL/TTL encoder, the speed change has exceeded the value in p0492. The manuals print the code under two headings — Encoder 2: Speed change not plausible (alarm) on the S120/S150 and Encoder 2: Speed difference per sampling rate exceeded on the G130/G150 — and word the cause accordingly: one manual describes a speed change over several sampling cycles, the other a speed difference between two sampling cycles. In both cases the change to the averaged speed actual value — where applicable — is monitored in the current controller sampling time. Depending on the drive configuration, the same condition can also be issued as a fault or as a message without reaction. Neighbouring Encoder 2 messages such as A32407, A32410, A32411, A32412, A32414, A32419, A32421 and A32422 are described on their own pages.

• For an HTL/TTL encoder, the speed change has exceeded the value in p0492 — one manual words this as a change over several sampling cycles, the other as a difference between two sampling cycles.
• The change to the averaged speed actual value — if applicable — is monitored in the current controller sampling time.

1. Check the tachometer feeder cable for interruptions.
2. Check the grounding of the tachometer shielding.
3. If required, increase the setting of p0492.

• The drive enters the alarm value from r2124 as the message value; interpret it as a decimal number.
• The manual states that this alarm value is only for internal Siemens troubleshooting.

• p0492 — square-wave encoder max. velocity difference per sampling cycle: the threshold the Encoder 2 speed change is monitored against; increase its setting if required once cable and shielding have been checked.
• r2124 — alarm value: holds the message value of this alarm; read it as a decimal number (only for internal Siemens troubleshooting).

As an alarm, A32418 needs no acknowledgment. If the drive is configured to issue the same condition as a fault, that fault must be acknowledged immediately; even then the reaction is none, so the drive does not change its operating state by itself.