DIYBMS v4

@Smurfix the background for this change was in this thread.

A lot of people have no issue with communication data being lost, others have had lots of problems. Most of the issues appear to be EMI style noise, others are different brands of inverters or the routing of data cables near power cables etc.

Most of the data comms issues appear to be between the last module and the controller (the RX line) therefore, a change was suggested as below. The change only costs a few pennies in parts, so seems reasonable if others have seen a benefit.