We need someone to help us search for a good low cost supplier of a communicating data acquisition board and sensors that we need to use to obtain data from HVAC-R equipment. We suggest the freelancer follow the following steps as part of this project.
1) Work with us to create a detailed specification of what we need that we approve.
2) Find suppliers through google searches and various product websites and then email them our request asking for what products they suggest and for quotations. Multiple emails or a phone conversation maybe required so they understand our requests. We may find a single supplier that can offer both the sensors and the board or we might need to purchase these from independent suppliers. You may need to speak with these suppliers on the phone. The supplier can be located anywhere in the world, but must be able to give support and documentation in English. We will ask for prices based on a quantity of 1 and then what volumes would allow for discounts. The suppliers may have options or features that enhance what we need.
3) Make a list of the suppliers that have products that will meet our needs. List these products and key features and the prices that you have obtained (sometimes you can even get from websites). Send this list to us. We will have questions that you can maybe answer or you will need to get the answers from the suppliers.
To complete the project a list of at least 10 potential suppliers or combination of suppliers along with prices that have a solution that can meet our needs and all questions about their solutions answered. The goal of the project is to find a solution that does what we need at the lowest cost.
Below is more detailed information that we need to source to give you an idea. This specification is not exact enough and will be completed in step 1 of this project together with your assistance.
We are looking to have a solution for putting extra sensors on HVAC-R equipment that is low cost and we can quickly implement.
-- We can connect to the Extra Sensor board via serial RS485 and read Modbus RTU data. We would then convert the serial to Ethernet and Modbus to XML to feed the data into our analysis system that is on our remote servers.
-- An alternative is if the supplier has a way to provide us the data via Ethernet directly. The preferred protocol would then be XML. We would also need to obtain this data via the internet and there is no fixed public IP address at our client's sites, so that means the extra sensor device would need to first connect to our server where there is a fixed IP address.
The hardware requirement is determined by the sensors we need to have.
We have Three Scenarios depending on the size of the machine we are monitoring. The idea is that we would have a main board and then 'expansion' boards to allow additional sensors to be connected.
BASIC (1 compressor refrigeration circuit machine):
-- 6 Temperature Sensors (NTC is fine)
-- 1 Low pressure transducer (-0.5 to 7 BAR)
-- 2 High pressure transducer (0 to 30 BAR)
= Total of 9
We would also like to have the ability to put a 'relay' on the compressor circuit so we can understand if the compressor is on or off and at what load percentage it is running at. We need to identify the specification of this relay.
TWO Circuit Machine:
-- 9 Temp. sensors
-- 2 Low pressure transducer (-0.5 to 7 BAR)
-- 4 High pressure transducer (0 to 30 BAR)
= Total of 15 sensors
+ 2 relays to understand Compressor Status
THREE circuit (compressor) Machine:
-- 12 Temp. sensors
-- 3 Low pressure transducer (-0.5 to 7 BAR)
-- 6 High pressure transducer (0 to 30 BAR)
= Total of 21
+ 3 relays to understand each of the Compressor Status
We need to source the sensors mentioned above as well either from the same company or a different one. The sensors used will also determine the acquisition board requirements. For example if pressure sensors with 4-20 are used and NTC temp. sensors...
We can be flexible in our requirement with the supplier to have a better chance of them having what we need and with a low cost.
Look forward to any questions or clarifications.