Now we have decided to create a simple calculator that makes it very easy to play around with these parameters to see the effect and to figure out how fast they can really go.īelow, we will walk through the calculator and explain the various parameters in more detail. We have always helped our customers calculate this communication time for their networks, and it is very useful for them to see how adding in more devices or changing the amount of process data will affect things. Now, with the introduction of EtherCAT G and G10, there are further variables in calculating the communication time. Beckhoff and the ETG refers to this as the total "communication time," which takes into account the complete time for sending the frames, the propagation delay through the network, and the time for receiving the frames. Of course, there is no straight answer to this question, as the cycle time not only depends on the specific application, but also on the number of devices in the network and the amount of data that will be sent in each cycle. Our customers often ask us, "What is the fastest cycle time I can achieve with EtherCAT and your Master software (EC-Master)?" Since EtherCAT is the fastest industrial Ethernet protocol, it is typical that our customers want to know just how fast they will be able to run their application with EtherCAT. 8 bit checksum: Sum on all bytes, modulo 256.ħ bit width CRC.EtherCAT Cycle Time Calculator Walkthrough An alternative checksumSpec text for the same checksum type would be: Used for example in MMC/SD card applications. See the "CRC: width, polynomial." syntax described in the last row.Ĩ bit width CRC, e.g. Same as:Ĩ bit width CRC known as DOW CRC or CCITT-8 CRC. Can be found in Dallas iButton(TM) applications. Same as:ġ6 bit width CRC as designated by CCITT. Same as:ġ6 bit width CRC as used in IBM Bisynch, ARC. Same as:ġ6 bit width CRC as used in Modbus. Similar to CRC-16, but with a different init value. ![]() Same as:ĬRC:32,04C11DB7,FFFFFFFF,FFFFFFFF,Yes,Yes Same as:ģ2 bit CRC as used in PKZip, AUTODIN II, Ethernet, FDDI. Similar to MOD256, but returns the negative 8 bit result, so the sum of all bytes including the checksum is zero. This is equivalent to what is known as LRC (Longitudinal redundancy check) used e.g. ![]() Generic CRC calculator, where all CRC parameters can be set individually: Like -MOD256 / LRC, but it expects the source data to be HEX numbers as readable ASCII text. The initial remainder to start off the calculation.įinalXor : HEX value. Apply an XOR operation on the resulting remainder before returning it to the user. ReflectedInput : Yes = Reflect the data bytes (MSB becomes LSB), before feeding them into the algorithm. ReflectedOutput : Yes = Reflect the result after completing the algorithm. This takes places before the final XOR operation.Įach of the predefined CRC algorithms (CRC-8, CRC-CCITT. ) can be replaced by a specification string for the generic CRC computation (CRC:8,07,00.) as described above. We have carefully tested and cross-checked our implementations against common literature and resources as listed in the CRC Glossary. Unfortunately there are a lot of CRC variations and algorithms around, and choosing (not to mention: understanding) the right CRC flavor can be a rather difficult job. In the Checksum tab, choose one of the predefined definition strings from the drop-down list, or type in your own definition in the following format: This is the most commonly used testing string, and many specifications will refer to this string and provide you the correct checksum the CRC should return when applied on this string.Ĭhecksums in Edit Send Sequence / Edit Receive SequenceĪ good way to make sure your CRC calculation makes sense is to run it over an ASCII test string of "123456789". With anything inside being an optional part. String that specifies the checksum algorithm and its parameters, according to the checksumSpec Format table above. Start and length of the character area that is used to calculate the checksum. By default everything before the checksum result is used. If used, the resulting checksum value is converted into a HEX number as readable ASCII text. Little Endian - the resulting checksum value is stored with the least significant byte (LSB) first. ![]() Specifies the first character position for storing the resulting checksum value.īy default Docklight writes the checksum result to the last sequence data positions, unless you have specified "A" for ASCII result.
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