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Siemens 6FC5357-0BB21-0AE0

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Part Number6FC5357-0BB21-0AE0
Model #6FC53570BB210AE0
Warranty2 Year

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MRO Electric repairs CNCs, PLCs, Servo/Spindle Drives, Motors, Amplifiers, VFDs, HMIs, and more, most of which can be repaired in only 3-5 days.

Repair Benefits

MRO can restore your failed 6FC5357-0BB21-0AE0 to remanufactured condition and save you up to 75% compared to buying new. We offer standard repair pricing to ensure you the best value for your repair.

Our certified technicians use rigorous testing procedures to ensure your parts are restored to fully functioning condition. Our team proudly stands behind all repairs by providing a minimum 2-year warranty.

Our technicians have vast experience with most manufacturers and models. In addition to this 6FC5357-0BB21-0AE0 we also repair a wide range of other Siemens products, so if you don’t see the model you need, please contact us.

Core Exchange

If you are interested in getting credit for your faulty 6FC5357-0BB21-0AE0, just let us know, and we can issue you an RMA to send it in as an exchange. Our exchange program provides you with savings and keeps us stocked for the next time you need anything.

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Ask about exchanging your faulty 6FC5357-0BB21-0AE0 for credit when ordering from MRO Electric

MRO Electric provides a 2-year warranty on every item we sell and repair. We stand behind all of our products and guarantee them for the full 2 years. If there is an issue with any of our products within the warranty period, we will evaluate the unit and repair or replace it under warranty.

Siemens 6FC5357-0BB21-0AE0 Overview

The 6FC5357-0BB21-0AE0 is an NCU, Numeric Control Unit, hardware module manufactured by Siemens. This module is compatible with and manufactured for the SIMODRIVE 611 D/DE module series. The Siemens 6FC5357-0BB21-0AE0 module is the computer numerical control (CNC) for the 840 D.  The 840 D is operated combining the power supply of SIMODRIVE 611 and a drive processor module such as the 6FC5357-0BB21-0AE0. The 6FC5357-0BB21-0AE0 CNC is responsible for automated control of machining tools. This module is the central processing unit taking on the communication tasks as well as the CNC and PLC.  These products are manufactured in Germany and are designed for Automotive, aerospace, power generation, and electronics usage. They come with a 2-year warranty from MRO Electric. We also carry Accessories from other manufacturers such as FANUC and Yaskawa.

Features of the NCU

A description of the components of the Sinumerik 840 D/DE processor module is as follows.  There are eight (8) components that make up the Sinumerik 840 NCU. There is a NCU box which is the module rack of the NCU unit. It is comprised of three parts. The first part a NC rack assembly and cable distributor, the second is a battery / fan module that slides into the unit, and the third is the housing unit made of sheet metal. The integrated side bars of the housing unit are where the battery / fan modules go as well as the power supply unit. 

The next component that makes up the NCU is the fan box.The fan box is a requirement for the 573.3 Pentium III and the 573.4 Pentium III NCU’s. The fan box can be mounted to the NCU box if needed. 

The third part of the NCU is the PLC module. The PLC module is a support unit. It adds to the system monitoring and is consistent with a PLC-CPU that goes with the family of S7-300 modules. For every eight peripheral S7-300 units, you can connect up to three external lines. This is done by way of the P bus. The PLC is a submodule of the NCU. 

The fourth module that helps make up the NCU is another sub module, the COM module 187.5 kBd/1.5 MBd. It is a communication module that facilitates communication between the PCU and peripheral units. 

The next module in the NCU group is the driver module. The driver module is another sub module for the NCU. This module forms the interface between modules. The Siemens 6FC5357-0BB21-0AE0 does this task. It is responsible for the communication.  For which units does it help facilitate communication? It serves as operator interface for the operator panel front, the programming device, the decentralized peripherals and the S7-300 peripheral modules. 

The final part the NCU is the PCMCIA card.  The PCMCIA card is where the bulk memory for the NC system software is stored. How does this work? The NCU has a plug-in unit for the PCMCIA card that is standard. Through the plug-in, type II flash cards with up to 8 MB of storage can be operated.  It also assists in software upgrade and series start-up.

Advantages of the Siemens 6FC5357-0BB21-0AE0




NCU 573.5B

1.4 GHz

128 Mbyte



Contact Us Today For More Information About Siemens Products

Check out the rest of our Siemens product line. Whether it's using our online instant quote feature, giving us a call at (800) 691-8511, or emailing us at, we strive for customer satisfaction first. This means lower prices and better service for you. For more products like 6FC5357-0BB21-0AE0, take a look at more from our Accessories line. If your current unit has gone bad, take advantage of our Core Exchange program for the most inexpensive route. You can learn more about this program on our FAQ page here. We offer a repair service on all of our 6FC5357-0BB21-0AE0 products that keep your downtime to a minimum. To stay up to date on manufacturer news, as well as access any of our datasheets, manuals, or other documentation, we suggest you take a look at our blog.

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I needed a special drive, found it, and I was quickly assisted by Joe Kaminski. Everything was exactly as it should be....


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