R36US0002EU0100 Rev 1.00
Page 2
Aug 26, 2021
RTD120D-EVK Evaluation Kit Software Manual
Contents
2.1 Installing DAQFactory Express . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2 Board Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.3 Establishing a Connection with the EVK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.4 Monitoring CO
Concentration and Sensor Readings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
3. Appendix A: Background Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4. Appendix B: Terminal Mode Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5. Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
1. Connection Modes
The EVK supports two modes of operation when connected to a host computer. Both modes, ModBus mode and
terminal mode use the same USB connection. When the EVK powers up, it immediately operates as a
stand
-
alone CO
2
detector as described in the
RTD120D-EVK CO
2
EVK User Manual
, with the integrated LCD and
push-button switches acting as the primary user interface. In the background, the USB interface is continually
monitored for an incoming connection. When a USB connection takes place, the first data byte received from the
host computer determines which protocol will be used.
If the first byte is binary 0, 1, 2, 3, 4, 5, 6, or 7, it assumes a ModBus client is attempting to talk to it. When this
occurs, the EVK operates in
ModBus mode
until the next re-start. Acting as a ModBus agent, that byte and all
subsequent received bytes are separated into packets and interpreted as ModBus requests. If the first byte is
anything other than binary 0, 1, 2, 3, 4, 5, 6, or 7, it is assumed to be part of a text command. The remaining bytes
are interpreted as characters of a text command, and the EVK operates in terminal mode until the next re-start.
Regardless of the communication modes (
ModBus mode
or
terminal mode
), the EVK continues to execute the
same algorithms and support the LCD/push-button user interface, even while a host computer is interacting with
the kit using one of these two protocols.
1.1 ModBus Mode
Any ModBus client running on a Windows, Linux, or Mac host computer can be used as long as the client is
configured to use the ModBus RTU protocol over USB. To get up and running quickly using ModBus, support files
are provided for using the DAQFactory
®
Express application by AzeoTech
®
, which can be downloaded for free
). These support files can be downloaded from the
product
page under “software”, and they configure the GUI for various use cases, such as to show live graphs of sensor
readings and related variables, and to provide a set of controls and graphs for an enhanced calibration user
experience.
1.2 Terminal Mode
In terminal mode, text commands can be sent over USB from a terminal program or a user’s application which can
be written in any language and framework that supports serial communication.
