Hello, So at work the goal is to send I2C commands to a Port Expander (PN:MCP23017) but I am completely lost also semi-new to LabView anyways. I understand at a high level what needs to happen in order to write to the Port Expander. Datasheet says I need to first write to it and "Define I/O Direction" then after this is defined I can write to send the actual data. I downloaded the NI-845x drivers and I have all the I2C vi's available. I'm just so lost on how to actually code this and write anything. I feel like I'm missing an extra write step for defining the I/O direction but I don't know. I keep getting the Error -301742 which says "The slave did not acknowledge an address+direction byte transmitted by the I2C master." The following is my attempt so far....

@GeneralDynamic wrote: What do you mean the I2C example that ships with LabVIEW? How can I get this? Go to Help, Find Examples. In the "Search" option, type I2C. Click on what it finds. I've attached the 2019 845x "General I2C Write" VI as a Snippet -- it has no "hidden states", so you should be able to manually reproduce it. I've never used I2C (but have used the SPI examples, and "think I understand SPI"), so I can't offer much additional help (like why there are references to EEPROMs). Some of the other examples might be more appropriate. I'll note that writing code for the SPI version of your chip was pretty straight-forward. Bob Schor

LabVIEW

MCP23017, I2C LabView HELP PLEASE.

Solved!

Hi,

What is the Packet Format to write and read the data. Datasheet has SPI Control Byte format and SPI Addressing Registers among these there is only filed for the Address what about the data to be written on the register? if you happened to know the Packet format to read and write please reply.

Thank you.