Syntax for generic `reply` function

[node-modbus]

Syntax for generic `reply` function

[dresende]

Yes, the reply assumes a first (fixed) argument for an error, and then the remaining arguments depend on the function code and what the standard defines for a response.

[jacobq]

Yes, the reply assumes a first (fixed) argument for an error, and then the remaining arguments depend on the function code and what the standard defines for a response.

OK, thank you for clarifying that. Is it the same regardless of whether reply is obtained from a specific event like read-coils vs. from the lower level request event?

connection.on("request", (request, reply) => {
    // ...
});
connection.on("read-coils", (request, reply) => {
    // ...
    // does this `reply` have the same signature/contract as the one above?
});

[dresende]

Is it the same regardless of whether reply is obtained from a specific event like read-coils vs. from the lower level request event?

I believe yes. But perhaps, in that case, it makes more sense to be able to send a raw response. You could just ignore the reply and write a response yourself, but it would be easier.

[jacobq]

OK, thanks for the reply. I will plan to just keep using the request event and it's reply function as I have it (like above -- seems to be working OK). It just feels a little non-intuitive because the library code does some of the protocol work (e.g. ID & function code / exception code) but not all of it (e.g. start address & number of coils/registers), so I have to dig into the library code to see what I need to do. For example, should I be sending "one big buffer" or separate arguments for, say, start address and array of data.

You could just ignore the reply and write a response yourself

Would that look something like this: transport.write(<Buffer>)? (Where <Buffer> holds the "Protocol Data Unit (PDU)")

[dresende]

Yes.

[jacobq]

Closing due to inactivity