J
sir/madam,
We are a group design engineers working on a Safety critical project. We were intersted in useing MODBUS protocol for some of the non vital communication links involved in our project.
As per the requirements, we have to achieve a hamming distance of minimum 5.
The use CRC-16 does not permit this as the hamming distance of CRC-16 is 4.CRC-32 seems to satisfy our requirement as it has a hamming distance of 5.
We are facing a problem with the number of bits assigned for error checking. The MODBUS protocol limits it to 16 bits. But we intend to use CRC-32 which requires 32 bits. It aslo allots 253 bytes for data. Our data will be around 128 bytes. so we plan to keep 32 bits for CRC. Having done that, can we still claim to have implemented modbus protocol.
we need this clarification, to be written in our documents. it would be kind of you, if you could answer this question of ours.
Thanking you.
your's sincerely
Jignesh v Mehta
DESIGN ENGINEER
REPD (R&D)
We are a group design engineers working on a Safety critical project. We were intersted in useing MODBUS protocol for some of the non vital communication links involved in our project.
As per the requirements, we have to achieve a hamming distance of minimum 5.
The use CRC-16 does not permit this as the hamming distance of CRC-16 is 4.CRC-32 seems to satisfy our requirement as it has a hamming distance of 5.
We are facing a problem with the number of bits assigned for error checking. The MODBUS protocol limits it to 16 bits. But we intend to use CRC-32 which requires 32 bits. It aslo allots 253 bytes for data. Our data will be around 128 bytes. so we plan to keep 32 bits for CRC. Having done that, can we still claim to have implemented modbus protocol.
we need this clarification, to be written in our documents. it would be kind of you, if you could answer this question of ours.
Thanking you.
your's sincerely
Jignesh v Mehta
DESIGN ENGINEER
REPD (R&D)