Configuring MB_SERIAL_MASTER

[TKrushel]

I have been attempting to establish a serial Modbus communication link between a 470 and a 334 using a MB_SERIAL_MASTER function block.  No object or address will connect to the MB_DATA pin in the MB_SERIAL_MASTER block. The HELP ON TYPE for this part of the block seems quite perplexing stating that there should be nothing connected to the input pin for a WRITE command and nothing on the output pin for a READ command. With no connection to the MB_DATA pin, the block will build, load, run, and display a SUCCESS message when triggered. Without a destination, however, it is not useful. What am I missing?

[TKrushel · Accepted solution]

I get to answer my own question! Turns out I am quite stubborn so I continued to work on this problem until I reached resolution. Help on Type instructions for the MB_DATA input and output pins have, unfortunately, been swapped. You do INDEED need to connect an array to the MB_DATA output pin to provide a destination when reading data from another station. Similarly, an array with source information must be connected to the MB_DATA input pin when writing data. And borrowing heavily from the Holy Hand Grenade sketch by Monty Python, the array size shall be 125. It shall not be 124. 126 is right out.