We have an old KWH meter that has been isnatlled more than 12 years ago. I was told that it's not easy to access the meter to look at it. But I was tasked to figure out if the exisiting calculations are correct for KW values.
The meter measures KWH. Every so many KWH it create a pulse which is...
I have a PLC that talks Modbus. I am going to use Modscan software running on my laptop (master), to pull data form the PLC (for initial testing purposes). The PLC have 3 terminal blocks for communications (+,- and shield).
In order for me to connect from my laptop comports (comm1, RJ485 to USB)...
If I Have a computer running Hyperterminal, and it's connected to the controller using serial commport-1. How can I use hyperterminal to test and trouble-shoot the serial communication. Can some one point me to a manual or a tutorial on how to use Hyperterminal to test serial communications...
We are installing VAV controllers in the ceiling plenum of a building. The controllers require 24V and each one is 10 VA rated.
How big of a 24V transformer can we install in the ceiling plenum to provide power to the controllers? What are the limitations by the NEC code? If the controllers, as...
When wiring input sensors as inputs to digital controllers, I sometimes see that a "IIM board" being used. My understanding is that they are used for electrical isolation between field devices and the controller.
My question is , when is it a must, and when is it an option? Or is it an extra...
I have a large commerical office building with a fully auomated systems. The HVAC (BAS) system is controlled by DCS controllers. It has multiple AHU units, VAV units, Chillers, etc.
I am trying to come up with sequences to save energy. We are already using economizer mode (free fresh air), when...
I am not sure if this is the right place to post this questions? But any way..
I have a large commerical office building with a fully auomated systems. The HVAC (BAS) system is controlled by DCS controllers. It has multiple AHU units, VAV units, Chillers, etc.
I am trying to come up with...
Recently I installed a "RS485" connection between our controller and a third party controller. It was specified that one must connect terminating resistor on each end of the RS485 loop (because it's a long run). It says that resistor is designed to match the electrical impedance characteristic...
I am a mechanical engineer, and I work in the building automation industry. I often come across many engineering disciplines. I have been, for the most part, on the software side (programming of controllers and IT) for quite a while now.
I would like to learn more about the hardware (field...
we have a data center were the power supplied to the computers is 175 KW.
I calculate the coolig tonnage independently using the following formula:
Tons = GPM X DelatT /24.
where GPM is measured water flow in GPM.
deltaT is (Supply - Return) CHW temp.
This formual produces ~ 40 tons when the...
I am an ME, and I work in the industrial automation industry. I am trying to learn Control Circuits Design, and I don't know exactly how to approach this.
I can grasp the theory without much effort, but I need more practical knowledge.
What I am trying to do is build some circuits, and...
Right now I work in the Building Automation Industry, and I do a lot of “Sequence of Operation “ programming using company's proprietary upper level structured language (similar to BASIC or FORTRAN). The Hardware/Software I am using is not widely used, and I don't use ladder logic diagrams.
To...
