wwsmith
Member
I am designing an hvac control system for my new 4800 sf office. I am going to use a server quality PC running in a clean conditioned environment with a pared down very stable Windows 7 operating system installation. I will use USB devices to read sensors and control outputs. I am writing the controls software in VB6 as there is no need for this application to be fully web enabled. For anything needing to be done remotely, I will use something like gotomypc.
There will be a lot of analog inputs and outputs, about 16 of each plus some digital inputs for occupancy sensors and the status of various devices. The analog inputs will be for reading various temperatures and pressures and the analog outputs will control a vfd for fan speed, modulate a valve to control water flow (ground source heat pump system), and control six modulating damper motor actuators to adjust air flow in the duct system.
Although this forum is mostly about using PLC's for control systems, I believe the question I have is relevant because it mainly involves how to sense and display data for a certain situation.
At each of the six different zones of the building, I want to have a wall mounted device that shows the current air temperature at that location as well as the current user set point temperature, nothing else.
Sounds almost like a regular thermostat right? But not really, because the temperature should be derived from an analog input temperature sensor (probably rtd) that connects back to a USB device like this one http://www.mccdaq.com/usb-data-acquisition/USB-TEMP-Series.aspx
So the computer sees the temperature from this sensor and someone standing there sees the same temperature on a digital display with one decimal format like 75.4 In addition, another display just below, shows the set point temperature in similar format. There are two push buttons on the device. One raises the setpoint temp and the other decreases it. That's it. There are no mode indicators for heating, cooling or fan operation. The software at the controlling computer limits the upper and lower ranges of the set point temp so if a user continues to hold a button down too long, the setpoint temp on the display does not go beyond the allowed range.
The controlling computer then adjusts the appropriate duct damper (fully modulating) to try an achieve the set point air temperature.
So is there any off the shelf temperature sensing and dual display device such as I described above? And if not, must I cobble together an analog temp sensor and some kind of digital counter sensor to count the button pushes in either direction and pair both of these inputs (actual temp and setpoint temp) with their own digital panel meter type displays?
What is the easiest way to accomplish what I described above?
There will be a lot of analog inputs and outputs, about 16 of each plus some digital inputs for occupancy sensors and the status of various devices. The analog inputs will be for reading various temperatures and pressures and the analog outputs will control a vfd for fan speed, modulate a valve to control water flow (ground source heat pump system), and control six modulating damper motor actuators to adjust air flow in the duct system.
Although this forum is mostly about using PLC's for control systems, I believe the question I have is relevant because it mainly involves how to sense and display data for a certain situation.
At each of the six different zones of the building, I want to have a wall mounted device that shows the current air temperature at that location as well as the current user set point temperature, nothing else.
Sounds almost like a regular thermostat right? But not really, because the temperature should be derived from an analog input temperature sensor (probably rtd) that connects back to a USB device like this one http://www.mccdaq.com/usb-data-acquisition/USB-TEMP-Series.aspx
So the computer sees the temperature from this sensor and someone standing there sees the same temperature on a digital display with one decimal format like 75.4 In addition, another display just below, shows the set point temperature in similar format. There are two push buttons on the device. One raises the setpoint temp and the other decreases it. That's it. There are no mode indicators for heating, cooling or fan operation. The software at the controlling computer limits the upper and lower ranges of the set point temp so if a user continues to hold a button down too long, the setpoint temp on the display does not go beyond the allowed range.
The controlling computer then adjusts the appropriate duct damper (fully modulating) to try an achieve the set point air temperature.
So is there any off the shelf temperature sensing and dual display device such as I described above? And if not, must I cobble together an analog temp sensor and some kind of digital counter sensor to count the button pushes in either direction and pair both of these inputs (actual temp and setpoint temp) with their own digital panel meter type displays?
What is the easiest way to accomplish what I described above?