AMG11P29Z0 is an encoder model that has become difficult to source, and the original version has been unavailable for some time. As a heavy-duty absolute encoder commonly used in metallurgical applications, it is still required as a spare part on a number of legacy machines. Once the original product became unavailable, replacement became a practical problem for some end users.
A few years ago, I was involved in the custom development of a replacement for this model. The project was commissioned by a steel mill in northwestern China. Their stock of AMG11P29Z0 spare units had already been exhausted, while the installed encoders could require replacement at any time, so the development schedule was relatively tight.
The development process went smoothly. The mechanical design was matched to the original installation requirements, including the ø11 mm solid shaft and ø115 mm B10 flange. The original AMG11P29Z0 uses a 9–30 VDC supply, while the custom version uses 10–30 VDC. For equipment already operating above 10 VDC, this difference normally does not affect practical use, but the actual supply voltage should still be confirmed before replacement.
There are two differences in this project that are especially worth discussing: resolution and the GSD file.
1. Resolution Difference
The original AMG11P29Z0 is a Profibus multi-turn absolute encoder with a single-turn resolution of 8192 steps (13 bit) and a multi-turn range of 65536 revolutions (16 bit).
For this steel mill project, we did not simply duplicate the original multi-turn range. Instead, the custom version was configured according to the actual application requirements:
Single-turn: 8192 steps · Multi-turn: 4096 revolutions
In other words, the single-turn resolution remained unchanged, while the multi-turn range was reduced from 65536 revolutions to 4096 revolutions.
This is one of the most important application differences between the custom version and the original AMG11P29Z0. If the actual machine only requires a total measuring range within 4096 revolutions, there is no need to mechanically reproduce the full 65536-revolution range of the original encoder.
However, before making such a replacement, the PLC program, scaling settings, and the actual multi-turn range used by the machine should still be checked carefully.
2. A New GSD File Is Required
AMG11P29Z0 uses Profibus-DP communication. According to the original AMG 11 documentation, the Profibus version uses Profibus-DPV0 and supports position value transmission as well as functions such as Preset, rotation direction, and Scaling.
The custom encoder also uses Profibus-DP, but it is not the original device itself. For this reason, the PLC configuration must use the new GSD file supplied for the custom encoder rather than treating the original device file as fully interchangeable.
For an electrical engineer familiar with Profibus, replacing the GSD file and reconfiguring the device is usually not a major task. For trading companies or purchasing staff responsible mainly for spare parts, however, this point should be clarified before the order is placed.
Otherwise, it is possible to reach a situation where the encoder has already been mechanically installed, but the PLC cannot recognize it as the original device.
Over the past few years, this custom AMG11P29Z0 solution has gradually moved beyond its initial applications in northwestern China. It has also been supplied to customers in northeastern China, southwestern China, Hebei, as well as Russia, the Middle East, India, and South America.
The order quantity for this type of product is usually small. Most orders are for only a few units, commonly three to five pieces at a time.
This is fairly typical for custom replacements of legacy industrial encoders. The quantity required for each individual project may be limited, but the equipment is still operating and the spare-part problem still needs to be solved.
The first customer carried the initial development work and development cost. Later customers benefit from that earlier project because the product has already been developed and applied in practice. For subsequent orders of the same configuration, the customer normally only needs to pay for the product itself rather than fund a complete development project again.
The photos in this article show the actual custom-developed AMG11P29Z0 replacement.
At present, this product is still manufactured on a custom-order basis rather than kept as a standard stock item, so a certain production and delivery lead time should be expected.
For similar replacement requirements, it is advisable to confirm the complete original model number, actual supply voltage, required multi-turn range, and Profibus configuration requirements before placing an order.
