Introduction

The sealed linear encoders of the LC xx3 series have established themselves very successfully in the market.  With the new LC xx5 generation, HEIDENHAIN will complement its current product program. The development of the encoders was focused on the requirements for purely-serial absolute systems.

Advantages of the New LC 1x5 and LC 4x5 Linear Encoders

• Support of new interfaces
  The LC 1x5 and LC 4x5 series support EnDat 2.2 (up to 16 MHz) and the new interfaces from Fanuc (αi), Siemens (DRIVE-CLiQ) and Mitsubishi (High Speed Interface up to 5 MHz).

• Higher resolutions
  The resolution of the LC 115 and LC 415 with an accuracy grade of 3 μm was increased from 5nm to 1nm. The resolutions of the encoders with Fanuc, Siemens or Mitsubishi interface were largely matched to those of the EnDat encoders.

• Functional safety for encoders with EnDat 2.2 or DRIVE-CLiQ interface
  Functional-safety (FS) versions will be available for the EnDat 2.2 (purely serial) interface and the DRIVE-CLiQ interface. This means that these encoders can be used as single-encoder systems in safety-related  applications - such as in axes with linear motor. In addition to the safe processing of the position values, these encoders  provide fault exclusions for the loosening of the mechanical coupling for various types of mounting.

• Optimized sealing design—Double sealing lips on the LC 1x5
  The sealed linear encoders can be purged with compressed air to increase the degree of protection. However, there are occasional encoder failures in the field, which are due to the introduction of contaminated compressed air. In order to counteract this problem in the field, a new sealing design was developed for the LC 1x5.The encoder features two successive pairs of sealing lips. The compressed air is conducted into a "chamber" between the pairs of sealing lips (only if the compressed air is connected at the housing!). Thanks to this design, during operation there is only a slight exchange of air between the interior of the housing and the chamber between the pairs of sealing lips. The main stream of sealing air flows from the inside out. Therefore, hardly any contaminated compressed air enters the scale housing. As a result, the interior of the encoder is  better protected from contaminated compressed air.
  
  Please note: In spite of the double sealing lips of the LC 1x5, clean compressed air must continue to be used. The double sealing lips only increase the tolerance to partly contaminated compressed air. Contamination of the interior of the encoder cannot be prevented if permanently contaminated compressed air is introduced.

• Reduced height of the LC 4x5 scanning unit
  The height of the LC 4x5 scanning unit was reduced to the dimensions of the LS 400 series. The mounting holes remain identical to those of the LC 483, so the LC 415 can be mounted unaltered to existing geometries.

Interfaces, Resolutions, and Functional Safety Compliance

HEIDENHAIN EnDat 2.2 Interface:
The maximum transmission rate of the LC x15 purely serial EnDat 2.2 encoders was increased to 16 MHz. The encoders are backward compatible regarding the transmission rate, because they can also be operated at lower clock frequencies.

The resolution of the 3 μm encoders was increased to 1 nm (the 10 nm resolution of the 5 μm encoders remains unchanged). Also, instead of 32 bits, 36 bits is used to transmit the position value. These two changes can result in incompatibilities in the customer's implementation of the EnDat interface, and must be tested if necessary. Aside from the differences described, in purely serial EnDat 2.2 mode the encoders are compatible to the LC x83. The encoders with functional safety can also be operated with standard EnDat 2.2 (without Pos2, without forced dynamic sampling).

The EnDat 2.2 purely serial interface provides mechanisms for safe transmission of the position value (2nd position value, additional error bits, forced dynamic sampling, etc.). EnDat 2.2 purely serial interface can be used on safety-related axes (e.g. on linear motors).

Siemens Interface:
Like the EnDat encoders, the encoders with DRIVE-CLiQ interface will also be introduced with resolutions of 1 nm and 10 nm. DRIVE-CLiQ can also be used on safety-related axes.

Fanuc Interface:
The LC encoders with Fanuc interface meet the requirements of the new "transmission type 5" and can be connected to α-mode and αi-mode Fanuc controls. The encoders feature both interfaces and automatically recognize the operating mode equired by the control. When the encoders are operated in α mode, their behavior is compatible to that of the current LC x93 F encoders. During operation in αi mode, their position values have a higher resolution (1.25 nm or 12.5 nm). This provides the advantage that the encoders are both compatible to the current LC x93 F and can be used in systems with the new higher-performance Fanuc hardware.

The Fanuc protocol does not contain any mechanisms that permit safe position-value transmission for linear encoders. It depends on the controls used whether the LC x95F can be used as a single-encoder system (e.g. on linear motors) in safety-related applications.

Mitsubishi Interface:
The Mitsubishi interface largely remains unchanged – the maximum transmission rate of the signals was increased from 2.5 MHz to 5 MHz. The resolution of the position values of the LC x95M is higher than that of the current LC x93M and matches those of the other interfaces.

The Mitsubishi protocol does not contain any mechanisms that safe position – value transmission for linear encoders. It depends on the controls used whether the LC x95M can be used as a single – encoder system (e.g. on linear motors) in safety related applications.

Mechanical Compatibility with LC xx3

LC 1x5
The LC 1x5 can be mounted to the same mating dimensions as the LC 1x3. However, since a new housing profile is used, the mounting aid for aligning the fixing element for the scanning unit of the LC 1x3 (ID 547793-01) cannot be used. At present, there is no appropriate mounting aid for the LC 1x5.

The LC 4x5 can be mounted to the same mating dimensions as the LC 4x3. However, a few details have changed (see below for further details).

Due to the changed geometry of the scanning unit, new mounting and testing gauges (ID 737 748) must be used for the LC 4x5. If the current gauges are used, mounting errors of the LC 4x5 may occur due to the changed mounting surfaces.

The standard LC 400 with the “small” end blocks (fastening with mounting spar) did not have any holes for fastening using the end block. The end blocks of the LS 400 have been provided with M4 oblong slots for some time now. In the past few years, many customers have changed from the LS 400 to the LC 400. Since a changeover to the LC without mounting holes was not possible for some of these customers, customized special variants were created.

The LC 4x5 will be provided with M4 oblong holes even if small end blocks (designation: A14) are used, so that the special variants will no longer be needed.

Important information: As with the LS 400, the end blocks with M4 screws should be used for fastening only in exceptional cases. The specifications of the encoders (temperature, vibration) apply to fastening with M8 screws or mounting with the mounting spar. M4 screws should be used for fastening only if low temperature variations and very low vibrations occur in the application.

Mounting aid – Nut retention
As with the LS 4x7, nut retention devices are also included in the items supplied with the LC 4x5. The plastic devices retain the nuts in the scanning unit. The clips were improved so that the nuts are prevented from spinning within the clips. If nut retention devices are used, however, it is no longer possible to move the mounting screws within the oblong slots.

With the introduction of the LC 415, a new mounting spar, the MSL 41, will be added to the product program. It will replace the current "universal mounting spar." The MSL 41 features several detail improvements and—in contrast to the current mounting spar—allows fault exclusion for the mechanical coupling. The dimension drawing for the MSL 41 is shown on the next page and can be found in the attached product literature.

Miscellaneous

Variable zero position of the scale substrate
A variable scale offset will be introduced for the LC xx5 due to manufacturing reasons. This reduces the cutting waste of glass substrates to a minimum during production and makes internal logistics much simpler. The offset is corrected in the scanning unit so that the absolute position output values correspond to the usual LC position values ("zero position" = 20 mm). This means there are no changes for the customer as far as complete products are concerned.

Important information! When the scanning unit is replaced, the offset in the scanning unit must be adjusted to the substrate. Therefore, a scanning unit can definitely no longer be replaced by the scanning unit of another encoder.

Lasered ID label—Changed contents
The ID labels of the LC xx5 are lasered onto the scale housing. This ensures that the ID label can no longer peel away due to the influence of media. This makes it easier to identify the encoder model if servicing becomes necessary. The following figures show examples of ID labels for the LC 115 and LC 415. Since the laser labeling can no longer be changed afterwards, the encoder index is not listed on the ID label. However, the encoder index can continue to be read from the electronic ID label, or be determined by means of Q studio if the serial number is known. The encoder index will continue to be printed on the packaging label. Hence it is still possible to determine the index of packaged encoders. The ID labels contain the "OS" data field in addition to the known information. The scale offset of the substrate is stored in this data field in encoded form. This value is required for replacing the scanning unit, if necessary.

Changed indication of vibration values in the specifications
Up to now, the vibration values indicated for sealed linear encoders applied to the entire encoder (composite values). In practice, however, it is advisable to indicate the vibration loads permissible for the scanning unit separately from those permissible for the scale housing. Experience in the field proves that the vibration loads acting on the scanning unit are significantly more critical than those acting on the housing. The scanning units are often mounted to brackets, which can intensify oscillations. The housings are usually mounted to the machine base, which provides sufficient damping due to its large weight.

For the new encoders, the vibration values for the housing are therefore indicated separately from those for the scanning unit.

For the LC 115, no distinction needs to be made between the vibration values permissible for the scanning unit and those permissible for the housing - a load of 200 m/s² is permissible for both the scanning unit and the housing.

Now the separation of values for the LC 415 shows distinctly that the vibration load permissible for the scanning unit is 200 m/s² for any type of mounting. This could not be clearly seen from the previous specifications. With the exception of one type of mounting, the values indicated for the housing correspond to the composite values that were previously indicated for the LC 4x3. If the "mounting spar and cable outlet at right" type of mounting is used, the value of 200 m/s² is indicated for the scanning unit, and the value of 150 m/s² is indicated for the housing—the value of 200 m/s² was indicated for the LC 4x3 for this type of mounting.

Click here to view the LC115 and LC415 Product Information Brochure