84 modules - last 4 not being read/used

[stuartpittaway]

As reported in the forum https://community.openenergymonitor.org/t/84-diybms-modules-not-working-as-expected/19261

84 modules in system, but last 4 not be read correctly after the first read.

[stuartpittaway]

To add, user is using 9600 baud on the modules, roundtrip is 4444ms.

[stuartpittaway]

Internal send queue is full during some operations, but not reported as an error or retried.