Frequently Asked Questions

Contact the office

01 Products with SMI interface

Is the power supply for an SMI LoVo drive defined uniformly?

No. As a rule, SMI LoVo drives are supplied with 24 V DC. However, other voltages are also possible. The supply voltage of the drive and the power supply unit must be matched to each other.

What must be considered when replacing an SMI drive with another brand?

SMI drives from different brands are compatible in terms of the interface. This means that the specified standard commands are executed in the same way on all drives and that the addressing procedures are identical.
When changing a brand or manufacturer, please note that functions, properties, and technical data of drives may differ. This includes, for example:
– maximum speed
– with or without creep speed
– with or without speed control
– adjustment procedures for end positions
– installation dimensions
– manufacturer-specific functions
– etc.

How long is an SMI certificate valid?

A product can be considered certified as long as it is registered on the website at https://standard-motor-interface.com/produkte/. A certificate has been issued for these products. Products that are not registered may not be placed on the market with the SMI mark.

If changes are made to a product or the requirements change, it may be necessary to repeat the certification process.

Where are SMI products registered?

All certified products are registered on the website https://standard-motor-interface.com/produkte/. A data sheet can be downloaded for each product.

What is an SMI certificate?

For products that have passed a testing and certification process, the office issues a certificate. The certificate number is listed for each product in the standardized data sheet. The certificate contains information on test reports and revision numbers of the specifications used.

How can I identify certified products with an SMI interface?

Certified products bear the SMI or SMI LoVo mark. In addition, certified products are registered on the website www.Standard-Motor-Interface.com.

02 Association SMI Standard Motor Interface e.V.

What opportunities do members of the SMI association have to participate and influence decisions?

  • Members can participate in the general meetings and work in working groups.
  • The technical working group deals with the further development of the standard and with addressing questions relating to the interface.
  • The marketing working group promotes the dissemination of SMI.

Participation in a working group enables an exchange of ideas within a professional network. In doing so, we ensure compliance with antitrust requirements.

Who can become a member of SMI Standard Motor Interface e.V.?

The following can be admitted as members of the association:

  • Suppliers of drives and controllers with an SMI interface
  • Suppliers of roller shutter or sun shading products
  • Planners or system integrators in the field of building automation
  • Users, operators, or providers in the field of building automation
  • Research institutes or associations

Is the Standard Motor Interface specification also accessible to non-members?

The currently valid specification can be obtained in paper form from the office against signature of a user agreement and payment of a fee.

Where are SMI products registered?

All certified products are registered on the website https://standard-motor-interface.com/produkte/. A data sheet can be downloaded for each product.

What costs are incurred for membership and for product certification?

The further development of the standard and the organization are financed through members’ contributions. There is an annual fee, a trademark fee, a certification fee, and a registration fee. The fee regulations are available from the office upon request.

How do you join the association SMI Standard Motor Interface e.V.?

The steps to membership in the association SMI Standard Motor Interface e.V. are as follows:

  • Contact the office
  • Complete a registration form
  • Sign a user agreement / trademark agreement

As a rule, the head of the office will seek a discussion with new members to get acquainted and to clarify any open questions. Corporate members receive access to the SMI documentation with updates.

After joining the association, the contributions become due in accordance with the fee regulations.

03 Planning, installation and commissioning

Is it possible to operate more than 16 drives via an SMI interface?

The SMI interface is designed for a maximum of 16 drives. There are also actuators or gateways that support a smaller number of drives on an SMI interface and describe this in the data sheet. If more than the permitted number of drives are connected, this can lead to malfunctions. There are also actuators or gateways that determine the number of connected drives and do not control any excess drives. Conclusion: For reliable operation, only the permitted number of drives may be connected.

Can an SMI drive be switched off to save energy?

The power consumption of a drive during idle phases can be further reduced by switching off the supply voltage. Such a procedure can be useful in commercial buildings, for example at night or on weekends. After switching back on, the drive is ready to receive a telegram after no more than 2 seconds.

What must be considered when switching between push-button operation and telegram operation, or vice versa?

SMI drives support both operating modes: push-button operation and telegram operation (see the planning manual).

As soon as a drive detects a connected controller, telegram operation is activated. The drive is ready to receive commands.

If the controller is disconnected and push buttons are connected, the drive must switch to push-button operation in order to evaluate the push-button commands. Switching to push-button operation is not implemented in the same way for all drive brands.

The following options are available:

  • The drive detects the absence of the controller and automatically switches to push-button operation
  • The DOWN and UP buttons must be pressed once in succession
  • The supply voltage must be briefly interrupted

If the drive cannot automatically detect the absence of the controller, the procedure is described in the operating instructions.

An existing sun shading automation system is to be replaced by a controller with SMI drives. Can the existing cables continue to be used?

Conventional sun shading controllers are usually implemented with four-core cables to the drives. SMI requires a five-core cable.

Are special cables required for the installation of SMI drives?

In residential or building installations, standardized 5-core cables can be used (NYM-J 5×1.5 or NYM-J 5×2.5). The conductor cross-section depends on the current requirement, the voltage drop due to cable length, and the loop resistance. The statutory installation guidelines must be observed.

For the installation of SMI LoVo drives, 4-core cables are required. No special requirements are specified. When dimensioning, attention must be paid to cable resistance and voltage drop, and the statutory installation regulations must be complied with.

When connecting an SMI drive, may the phase (L) and neutral conductor (N) be swapped?

The SMI drive is protected against swapping the phase (L) and neutral (N) connections and would not be damaged. However, the desired function is not guaranteed. SMI drives must be installed correctly according to the wiring diagram. Please also refer to the chapter “Installation” in the planning manual.

Which cable routing (topology) is possible with SMI?

Bus or star topology is possible; however, bus topology offers advantages in terms of wiring effort.

04 Tools for installation and testing

How can end positions be set on SMI drives?

Setting the end positions is the responsibility of the supplier of the roller shutter or sun shading system. The end-position setting is specific to the respective product and the drive. The end positions can be set using an adjustment cable.

05 Addressing of SMI drives

Can the KeyID be changed later?

No. Each KeyID is a uniquely assigned address from a manufacturer for the unambiguous identification of a drive.

How can the manufacturer code and the KeyID be entered in control systems?

The manufacturer code and the KeyID uniquely define an individual drive. Both codes are documented on the drive and can be shown in decimal or hexadecimal form:

  • Manufacturer code: 1..10 (decimal) or 1..A (hexadecimal)
  • KeyID: 0..4’294’967’295 (decimal) or 0..FFFFFFFF (hexadecimal)


Depending on the control system, the manufacturer code and the KeyID must be entered in the configuration tool. Care must be taken to enter the codes in the correct format. The KeyID can easily be converted from decimal to hexadecimal and back using a calculator in programmer mode.

There are also actuators that read the KeyID independently. The associated drives must then be assigned to the rooms afterwards.

With certain KNX actuators, the manufacturer code must first be entered in ETS and then the KeyID in the following section.

What addresses does a drive have?

A drive has three codes for identification:

The KeyID is a 32-bit address. Each KeyID is assigned only once by a manufacturer.

The manufacturer code is a code in the range 0..10. Together with the KeyID, the manufacturer code identifies a single drive, which occurs only once in this combination.

The slave address is a code in the range 0..15 and can be assigned to each drive as a short address.

06 Faults

Individual drives or a group do not execute travel commands correctly

The cause may be an installation error. The correct connection of the power supply must be checked. For STAS4 plug connections, L must be connected to terminal 3 and N to terminal 4. Swapping the connections can lead to malfunctions with longer cable runs.

Position query does not work for a group of drives

If two or more drives have the same slave address, travel commands work without problems. Read commands, such as reading out the current position, are not possible with such a configuration. For correct use of read commands, each drive must be programmed with its own slave address. The assignment of the slave address is provided via the SMI-easyMonitor program or via actuators. Drives with different slave addresses can be combined into groups using the group key.

Can one drive be used as a reference drive to control a group of venetian blinds?

When controlling venetian blinds, one drive could be used as a reference drive to monitor an end-position. When the reference drive reaches the end position, all other drives are stopped. This approach is not recommended, as 230 VAC drives may have slightly different run times.

SMI-easyMonitor

When using SMI-easyMonitor, faults may occur if:

  • Antivirus programs on the PC interfere with the process -> disable the virus scanner
  • the PC’s processing power is insufficient -> use a different PC

What reasons can lead to different slat positions in a group of venetian blinds?

With SMI drives, the slats of a venetian blind can be aligned precisely. If the slats are not aligned as desired, the following causes may apply:

  • the tilt gearboxes of the venetian blinds are unsuitable for precise slat positioning
  • the end positions are not set correctly
  • the slat is adjusted in many small steps and the steps are too small for reproducible slat positioning
  • the control commands for the venetian blinds differ due to the algorithms used

-> analysis using SMI-easyMonitor