Null Pointer Exception - ModbusTCP Master

[ed nelson]

I was getting a Null Pointer Exception when the ModbusTCP Slave was not connected.
I had to modify ModbusTCPTransaction.java
Changed line 201
From: while (retryCounter < (m_Retries > 0 ? m_Retries:1)) {
To: while (retryCounter <= (m_Retries > 0 ? m_Retries:1)) {

So the ModbusIOException would be caught and not allow code to proceed to
line 254 "if (isCheckingValidity())" where the Null Pointer Exception was thrown.

Thanks

[Julie Haugh]

Ed,

The solution I found previously was to protect the call to checkValidity() by verifying that message pointer was non-null.

You also found an issue with the original design in that there are off-by-one errors. m_Retries is initialized to 0. If you use "retryCounter <= (m_Retries > 0 ? m_Retries:1)" to terminate the loop, you will always get one more retry than you requested. The better solution is to fix the off-by-one problems.

I'll get that code change made and move the status to "Production" from beta once I get a new set of JAR files uploaded.