6ES7157-0AA81-0XA0 SIMATIC ET 200S IM 157
The Siemens SIMATIC ET 200S IM 157, part number 6ES7157-0AA81-0XA0, is an interface module designed for the ET 200S distributed I/O system. It belongs to the SIMATIC S7 product family and serves as the communication head for connecting ET 200S I/O stations to a PROFIBUS DP network. The module enables decentralized signal processing by linking field-level I/O modules to a higher-level controller such as a SIMATIC S7-300 or S7-400 PLC.
The 6ES7157-0AA81-0XA0 interface module communicates via PROFIBUS DP at data transfer rates of up to 12 Mbit/s, supporting both DP master and DP slave operating modes. It features integrated diagnostics and supports isochronous mode for time-critical applications requiring synchronized data exchange. The module operates on a 24 V DC supply voltage and is designed for installation on the ET 200S terminal module, providing a compact and modular architecture. It supports configuration via STEP 7 or TIA Portal engineering software.
The ET 200S IM 157 is widely used in manufacturing automation, automotive assembly lines, machine tool applications, and process industries where distributed I/O with high-speed PROFIBUS DP communication is required. Its modular design allows flexible expansion of I/O capacity directly at the machine or process level, reducing wiring complexity and improving system diagnostics. The module is particularly suited for applications demanding precise synchronization and fast cycle times in distributed control architectures.
Technical Specifications
| Series/Product Family | SIMATIC ET 200S |
|---|---|
| Module Type | Interface Module (IM) |
| Communication Interface | PROFIBUS DP |
| PROFIBUS DP Transfer Rate | Up to 12 Mbit/s |
| Input/Operating Voltage | 24 V DC |
| Operating Temperature | 0 °C to +60 °C |
| Storage Temperature | -40 °C to +70 °C |
| Relative Humidity | 10% to 95% (non-condensing) |
| IP/Protection Rating | IP20 |
| Mounting | ET 200S terminal module (rail-mounted) |
| Bus System Compatibility | PROFIBUS DP (IEC 61158) |
| Certifications | CE, UL, cULus |
| Configuration Software | STEP 7 / TIA Portal |
Common Diagnostic Fault Codes
- Fault Code 1
- Configuration error: The configuration stored in the IM 157 does not match the actual I/O modules present on the ET 200S station.
Check the hardware configuration in STEP 7 or TIA Portal. Ensure all I/O modules are correctly seated and match the configured setup. Download the corrected configuration to the CPU. - Fault Code 2
- PROFIBUS DP communication error: Loss of communication between the IM 157 and the DP master controller.
Check PROFIBUS cable connections, termination resistors at both ends of the bus, and bus address settings. Verify the baud rate matches the master configuration. - Fault Code 3
- Power supply fault: The 24 V DC supply voltage to the IM 157 is missing or out of tolerance.
Measure the supply voltage at the terminal module. Ensure the power supply unit is functioning correctly and the voltage is within the 20.4–28.8 V DC range. - Fault Code 4
- Module failure: One or more I/O modules in the ET 200S station have reported a hardware fault or are not responding.
Identify the faulty module using the diagnostic data in STEP 7 or TIA Portal. Replace the defective I/O module and verify correct seating on the terminal module. - Fault Code 5
- Isochronous mode synchronization error: The IM 157 has lost synchronization with the DP master in isochronous mode.
Check the PROFIBUS network load and cycle time settings. Verify that the DP master supports isochronous mode and that the configured cycle time is achievable given the number of slaves on the bus. - Fault Code 6
- Station address conflict: Two or more devices on the PROFIBUS network share the same station address.
Use a PROFIBUS diagnostic tool to identify duplicate addresses. Reassign unique PROFIBUS addresses to each device and restart the network. - Fault Code 7
- Watchdog timeout: The IM 157 has not received a valid data frame from the DP master within the configured watchdog time.
Check the PROFIBUS network for cable breaks or excessive noise. Increase the watchdog time in the hardware configuration if the network cycle time is long, or investigate and resolve network communication delays.
Frequently Asked Questions
What communication protocol does the 6ES7157-0AA81-0XA0 use?
The 6ES7157-0AA81-0XA0 uses PROFIBUS DP for communication, supporting data transfer rates of up to 12 Mbit/s. It can operate as a DP slave connected to a SIMATIC S7 or compatible DP master controller.
Is the IM 157 compatible with TIA Portal for configuration?
Yes, the ET 200S IM 157 can be configured using both STEP 7 (classic) and Siemens TIA Portal engineering software. The appropriate GSD or HSP file may be required depending on the software version used.
What is the supply voltage required for this module?
The 6ES7157-0AA81-0XA0 requires a 24 V DC supply voltage, typically in the range of 20.4 V DC to 28.8 V DC, supplied via the ET 200S terminal module.
Does the IM 157 support isochronous mode operation?
Yes, the IM 157 supports isochronous mode (equidistant bus cycle), which enables time-synchronized data exchange between the ET 200S station and the DP master for motion control and other time-critical applications.
Can the 6ES7157-0AA81-0XA0 be used with S7-300 and S7-400 controllers?
Yes, the ET 200S IM 157 is compatible with SIMATIC S7-300 and S7-400 CPUs acting as PROFIBUS DP masters, as well as other DP master controllers that support the PROFIBUS DP standard.
Troubleshooting
The SF (System Fault) LED on the IM 157 is lit red after power-on
This indicates a configuration mismatch or hardware fault within the ET 200S station. Connect a programming device running STEP 7 or TIA Portal and read the diagnostic buffer to identify the specific fault.
Compare the actual I/O module arrangement with the hardware configuration. Correct any mismatches, ensure all modules are firmly seated on their terminal modules, and download the updated configuration to the controller.
No PROFIBUS communication established between IM 157 and DP master
Check the BF (Bus Fault) LED on the IM 157. If lit, this indicates a PROFIBUS layer 1 or layer 2 communication problem. Verify cable connections, bus termination, and station address settings.
Inspect PROFIBUS connectors for damage or incorrect wiring. Ensure termination resistors are enabled only at the two physical ends of the bus segment. Confirm the PROFIBUS address set on the IM 157 matches the address configured in the DP master project.
ET 200S station drops out intermittently during operation
Intermittent dropouts are often caused by PROFIBUS cable noise, poor grounding, or marginal power supply voltage. Use a PROFIBUS diagnostic tool to monitor bus quality and check for repeated CRC errors or retry counts.
Improve cable shielding and grounding at all connectors. Verify the 24 V DC supply voltage remains stable under load. Reduce the PROFIBUS baud rate if the cable length is near the maximum for the selected speed.
Individual I/O module on ET 200S station not recognized after replacement
After replacing an I/O module, the IM 157 may report a configuration error if the replacement module type does not match the original or if the module is not fully seated on the terminal module.
Confirm the replacement module is the correct type and order number. Press the module firmly onto the terminal module until it clicks into place. If the fault persists, cycle power to the ET 200S station and verify the hardware configuration in STEP 7 or TIA Portal.
IM 157 does not power up and all LEDs remain off
Absence of any LED indication typically points to a missing or insufficient 24 V DC supply. Measure the voltage directly at the power terminal of the ET 200S terminal module.
Verify the power supply output voltage is within the 20.4–28.8 V DC range under load. Check wiring connections and any upstream fuses or circuit breakers. If the supply voltage is correct and the module still does not power up, the IM 157 may have an internal hardware fault and should be replaced or sent for repair.
| Condition | Repair, Used, Refurbished, New in box (sealed) |
|---|