V3 Multiple unitId on a single connection

[kevingarman]

My setup is a modbus tcp gateway with a handful of serial devices. Due to connection count limitations, I'm trying use a single socket to the gateway to communication with all serial units. I've done this with a single socket in the node app with multiple modbus tcp clients using the same socket. I believe is the intended usage but please correct me if I'm wrong.

I was getting a log of "request fc and response fc does not match" and "rejecting because of earlier OutOfSync error" errors. I believe the cause is that all ModbusClients using a given socket get notified of the incoming data on that socket and try to consume it without first verifying the unitId. I modified line 45 of modbus-client.js to the following:

if (!response || (this._unitId != response.unitId)) {

...and that seemed to make it work.

[stefanpoeter]

Exactly that is the intended way of using it.

[kevingarman]

Ok cool, but it doesn't work right...all modbus clients are notified of data on the socket and all try to consume the data even when the unit ids don't match. I don't know if this is the best fix but it seems to work #179

[stefanpoeter]

We need to extract the response first in order to validate the unitId. Seems like the best way to do this to me.