I am posting this with minor edits but it is what I received from Belgium a while back. When reading this, one should assume that the constraints regarding serial.match likely also apply to any 1-way RS-232 actions that might be running concurrently with your Prontoscript.

Behavioral Differences

Application version 7.2.23 introduces a fix for fast subsequent actions on the same extender.

A side-effect of this fix is a slight change in the behavior of asynchronous operation of a serial port from within ProntoScript.

Previously (application [firmware] version 7.2.22 and earlier), when a non-blocking serial.match(..) operation was not yet timed out, new serial.match() operations would fail (for asynchronously addressed serial ports, this failure is exhibited as a call to an onError handler, the match itself would not throw an exception).

[Beginning with] application [firmware] version 7.2.23 however, performing a serial.match() while a pending serial.match(..) is not yet timed out, will cause the pending match(..) operation to abort, potentially dropping already received data in transit.