SIMATIC FRONT CONNECTOR 6ES7392-1AM00-0AA0 6ES7 392-1AM00-0AA0 6ES7392-1AMOO-OAAO

Siemens 6ES7392-1AM00-0AA0 | SIMATIC S7-300 Front Connector — 40-Pole, Screw Contacts, AWG 19–24, 0–60°C, 21.6×125×40.9mm

Overview

The Siemens 6ES7392-1AM00-0AA0 is the 40-pole front connector for SIMATIC S7-300 signal modules — the wiring component that bridges the S7-300's process signals from the field into the PLC system.

In the S7-300 architecture, signal modules (the I/O boards that read sensor states and command actuators) are designed as two-part assemblies: the signal module itself stays in the cabinet on the mounting rail, and the front connector — this part — carries all the field wiring. 

The front connector can be removed with its wiring intact, and a new or repaired signal module can be installed in its place.

The front connector and its wiring then re-plug into the new module without any rewiring.

This separation between module and wiring connector is one of the S7-300 design features that genuinely reduces machine downtime. Without it, replacing a failed digital output module would mean identifying and removing forty individual field wires from the failed module's terminals, installing the new module, and re-terminating each wire to the correct terminal position. With the removable front connector, the replacement takes a few minutes: remove the front connector, swap the module, plug the front connector back in.

The 40-pole version (this part) is used with S7-300 modules that have 40 I/O points or 40 terminal positions.

Standard 32-channel digital modules and many analog modules use the 40-pole connector. The 20-pole version (6ES7392-1AJ00-0AA0 series) is used with smaller 16-channel modules.

Key Specifications

Screw Contacts — Reliable Field Wiring in Industrial Environments

The screw contact connection method used in the 6ES7392-1AM00-0AA0 is the established standard for industrial PLC wiring where long-term reliability and ease of maintenance take precedence over connection speed.

Each of the 40 terminal positions accepts a wire inserted into the terminal bore, with a captive screw that clamps the wire when tightened to the specified 0.4–0.7Nm torque.

Screw contacts handle the wire cross-section range of AWG 19–24 (approximately 0.14mm² to 0.75mm²) that covers the typical signal cables used in industrial control wiring: 0.5mm² single-core for short panel wiring runs, 0.75mm² stranded for longer sensor cable runs, and 0.25mm² for compact wiring in space-constrained panels.

Ferrule end-sleeves (Aderendhülsen) are recommended for stranded wire to prevent wire strand spreading under the screw, particularly important for fine-stranded flexible cables.

The alternative connection type — spring-loaded push-in contacts (used in the 6ES7392-1BM01-0AA0 spring connector variant) — offers faster wiring speed without a torque wrench, but the screw type is preferred in applications where periodic connector removal and re-insertion is expected, as spring contacts can lose preload over many insertion cycles. For the vast majority of S7-300 installations where the connector is wired once and remains in place, both connection types are equally reliable.

Field Coding — Preventing Rewiring Mistakes

The S7-300 front connector includes a field coding system: small coloured coding keys that can be inserted into the connector body and the corresponding module housing. Once a connector is coded to a specific module type, it can only be inserted into a module with the matching code — or into an uncoded module.

This prevents the accidental reinstallation of a connector wired for (for example) a 24V digital input module onto a 24V digital output module during maintenance, which would connect field actuator voltages to input terminal circuits with potentially damaging results.

The coding is applied by the commissioning engineer: after installing the connector on its correct module for the first time, the coding key is set.

If the connector is later removed for module maintenance, the code on the connector ensures it can only be re-installed on the correct module type.

Removable Front Connector — The Maintenance Benefit in Practice

The maintainability advantage of the removable front connector becomes tangible when a signal module fails in a production environment. Consider a 32-channel digital input module in a packaging machine that reads the states of 28 proximity sensors across the machine's mechanics.

If that module develops an internal fault, the failed module must be replaced.

Without the removable connector, the maintenance procedure involves: powering down the station (or using hot-swap procedures if supported), identifying 28 individual sensor wires plus power supply wires on 32 terminals, noting (or re-reading) each wire's terminal position, disconnecting all wires, installing the new module, and re-terminating all wires to their correct positions — typically 45 minutes to an hour of careful work, longer if the wiring labelling is unclear.

With the removable front connector, the procedure is: power down the station, press the connector release, pull the connector free (wires remain attached), install the new module, click the connector back in.

Elapsed time: typically under five minutes. The machine returns to production; the wiring remains untouched and free of re-termination errors.

FAQ

Q1: How does the 40-pole front connector differ from the 20-pole version, and which S7-300 modules use each?

The 40-pole connector (this part, 6ES7392-1AM00-0AA0) is used with S7-300 modules that have 40 terminal positions — typically 32-channel digital input or output modules (SM321/SM322/SM323) and most analog input and output modules (SM331/SM332).

The 20-pole connector (6ES7392-1AJ00-0AA0 series) is used with smaller modules that have 20 terminal positions — typically 16-channel digital modules.

The specific front connector type required for each S7-300 module is specified in the module's datasheet and in the SIMATIC S7-300 Module Specifications manual.

Q2: Can the front connector be re-used when replacing a failed S7-300 module?

Yes — this is the primary purpose of the removable front connector design. The connector with all its field wiring can be unplugged from the failed module and re-plugged into the replacement module without disturbing the field wiring.

The contacts in the connector are designed for repeated insertion and removal cycles. Good practice is to inspect the contact surfaces of both the connector and the module's mating interface before re-installation, and to verify that the coding (if applied) is still intact and correctly matched.

Q3: What is the maximum wire cross-section the front connector can accept, and are ferrules required?

The 6ES7392-1AM00-0AA0 accepts conductors in the AWG 19–24 range, approximately 0.14mm² to 0.75mm². For solid (single-core) wire, direct termination without ferrules is acceptable within this range.

For stranded wire, Siemens recommends using ferrules (end-sleeves) to prevent strand spreading under the screw contact — this maintains reliable contact over time and reduces the risk of inter-terminal short circuits from stray wire strands. The stripped wire length for insertion is 6mm.

Q4: The product is in phase-out since October 2023. How long will it remain available, and what is the alternative for new projects?

Phase-out (PM400) typically means Siemens continues to supply the product from existing production stock for a transitional period — often one to two years — before it becomes unavailable from Siemens directly. After that, the industrial surplus and distribution channel supply continues.

The broader context is that the S7-300 platform itself is being phased out in favour of the S7-1500. 

For new control system designs, Siemens recommends the S7-1500 with its own front connector range. For existing S7-300 installations requiring spare front connectors, the 6ES7392-1AM00-0AA0 should be procured while available from current distributors.

Q5: Can the front connector be wired with the module in place on the mounting rail, or must it be removed first?

The S7-300 front connector can be wired in either configuration — attached to the module on the rail (in situ wiring) or removed from the module and wired on the bench.

In-cabinet wiring is often more convenient during initial installation, as the connector can be partially inserted into the module in a "wiring position" that holds it in place while leaving the terminals accessible. 

After wiring is complete, the connector is pushed fully home and locked. Bench wiring is an option when the cabinet space is constrained or when wiring multiple connectors in advance before mounting the modules.