What is the length of the fieldbus message? Is it different for discrete and continuous variables?
The total message length can vary from 11 to 276 bytes (called “octets” in the fieldbus world), depending on the message type and data content. There are no extra start and stop bits, so at 31.25kbps, each byte takes 256 microseconds. The whole message could therefore take anything from about 3 to 70 milliseconds. Reading a single variable, whether it is discrete or continuous, would be near the shorter end of this range. For efficiency, several variables can often be collected into a single message.
