Bus Fault / Compressor Not Reachable — Sigma Air Manager 2 (SAM 2 / legacy SAM) Fault Code

Sigma Air Manager 2 (SAM 2 / legacy SAM)

If a plant is already running SAM 2 with mixed-vintage machines, confirm each machine's interface card before quoting a SAM 4.0 upgrade — the interface, not the master, usually drives the cost.

Manufacturer

Kaeser

Display

Monochrome graphic display with membrane keys (SAM 8/16 variants by machine count).

Years produced

~2004 – 2015. Superseded by Sigma Air Manager 4.0.

Power supply

100 – 240 VAC wall-mount enclosure, internal 24 VDC bus.

Ambient range

0 – 45 °C.

Protection rating

IP54 wall enclosure.

Relay outputs

Per-compressor enable relays, dryer enable, common alarm.

Replaced by

Sigma Air Manager 4.0

Used on

Mixed Kaeser fleets
Third-party compressors via contact interface

Features

3-Dadvanced control — pressure band, run hours and switching losses balanced together
Up to 8 or 16 compressors depending on model
Trend and energy logging exportable for audits
Remote alarm relay and modem callout on legacy builds

Interfaces

Profibus DP
Modbus RTU
Ethernet (later builds)
Volt-free contacts

Sensor inputs

Network pressure (primary and backup)
Dew point (option)
Compressor status via Profibus or dry contacts

Fault code lookup

Bus Fault / Compressor Not Reachable Profibus or Modbus slave stopped answering.

First checks

Unique address per machine
Termination resistors at the two physical ends
Check the bus connector switch position

See trigger conditions & affected models →

Pressure Sensor Fault Network transducer open or out of range.

First checks

Loop check 4–20 mA
Sense line isolation valve
Compare with a calibrated gauge

See trigger conditions & affected models →

Pressure Band Not Maintained Demand exceeds capacity or machines are in Local.

First checks

Every machine must be in Remote/SAM mode
Check for standing alarms on slaves
Verify isolation valves open

See trigger conditions & affected models →

Battery / Clock Fault Backup cell exhausted; logs and schedule lose time.

First checks

Replace the backup battery
Re-enter time and schedule

See trigger conditions & affected models →

Fault list is non-exhaustive and firmware-dependent. Always confirm against the controller’s on-screen help or OEM manual.

Sensor pin resistance & signal values

Pin-level resistance and signal values for the sensor types this controller uses. Works offline. De-energise the panel and lift one lead before ohming any element.

Wiring notes

Profibus requires the correct connector with termination switch — a mis-set switch takes down the whole segment
Fit a hardwired backup pressure switch so master failure cannot leave the plant without air

Known issues & field notes

Legacy SAM hardware and Profibus cards are increasingly hard to source; most upgrades go to SAM 4.0
Older units use a serial service port; a USB-serial adapter with a genuine chipset is required for parameter backup

Operator and service levels set at commissioning by the Kaeser dealer.

Manuals & literature

Kaeser — support portal

Manuals gated — request via local rep or parts portal

Browse all OEM manual portals →

Your manuals