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How can I establish static links to EtherCAT slaves
birddog
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12-12-2012 12:05 PM
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I am building a distributed data acquisition system that will collect data from several EtherCAT slaves both NI and 3rd party. The topology of the network may change in the future (eg. an additional node inserted half-way down the network chain) and I'd like to configure my software to automatically account for this change. The biggest problem I am encountering is that the NI EtherCAT Master arbirarily assigns names to slaves (eg. Device, Device2, Device3, ...) when the Refresh Modules VI is called and these names are used to build the URLs to the variable objects. When a new device is added, some of the names will then point to a different physical device. Any URLS pointing to desired IO points that were saved in a config file ar no longer valid. Is there a way to assign a permanent alias to slave devices such that a URL could remain static and functional as long as that device remains on the network? If not, is there another way to go about rebuilding the URL based on static information available on the slaves?
DirkW
NI Employee (retired)
12-13-2012 08:12 AM
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I would read the description property of each slave and build a cluster that has this description which is mostly the name of the device and the position address and then use a case that has all the descriptions in the selector to read and write the correct refnum and data. Of course you have to build that cluster whenever you restart the program and it would take care of topology changes.
DirkW
nibuddy1777
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03-03-2022 02:59 PM
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I know this is an old post but was wondering if cRIO Ethercat Masters support Ethercat Slave Station Alias (see link https://www.ethercat.org/download/documents/ETG1500_V1i0i2_D_R_MasterClasses.pdf section 5.5.4. )
5.5.4 Station Alias Addressing
Description
A slave can be addressed by a fixed address stored in SII; this address is called Configured Station
Alias. The Configured Station Alias address is loaded from SII to Register 0x0012 (Configured Station
Master Classes Requirement Specification
ETG.1500, EtherCAT Master Classes 13
Alias register) during Power-on of the device. The Configured Station Alias has to be enabled by the
master.
Reference
ETG.1000.4
