How Can IBM Bluemix Node-RED Iotout node be set up correctly to send command to Device (Arduino)?

Question

I have an Arduino Uno that is successfully registered as a device with IBM IoTF. It can send information to the Bluemix Node-RED app without any issues now. Now, I would like the Node-RED app to send commands to the device (the Arduino Uno). The Arduino is subscribed to the MQTT without any error. But, it is not receiving any commands from the Node-RED. I followed the directions at the link below to create another flow in Node-RED to show when a command is published and the commands are being shown, so they seem to be going to the MQTT broker. But, the device (Arduino) is not receiving them. How can I figure out how to get this working?

Node-RED, IOT Foundation Out Node Not Sending Commands

I have the IBM IoT Out Node parameters set as follows: Authentication: Bluemix Service Output type: Device command Device type: Arduino-tempsensor (this is the same string I used for the device type (name) when I registered it in IoTF) Device ID: I put the MAC address here, should it be more Command Type: status (I used the word "status" here. Does capitalization matter? Where should I get this value from? I used "status" because it is in the topic: "iot-2/cmd/status/fmt/json" is that correct?) Format: json (does capitalization matter here?) data: {"d":{"myName":"Arduino Uno", "temperature":989}} (I used this because it's JSON and I wanted to just see anything at the device) Name: IBM IoT App Out

Answer 1

I typed up this whole question and then it occurred to me that the test flow to look for the published command should have all of the parameters set to exactly the same as the output. When I tried that, I was not getting the command message coming back. Then, I realized that my mac address (device ID) was capitalized in one place, but not the other. The MAC address (Device ID) I used to register the device was all in caps, so I make the Iot-out node for the command so that it was all capitalized and made the Iot-in node to test for the message so that it was all capitalized. Now it works! Then, I looked back at the device (which was printing to the serial monitor so I could see what was happening) and I am now seeing the messages! So, make sure your parameters follow the same capitaliztion!