Monitor - ISSN 1472-0221
The Newsletter for Data Acquisition and Control
Issue 264 October 2020
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TCP/IP is a standard method for sending messages across a network. It is used on many networks including Internet and Ethernet.
It is a good idea when first connecting instruments to keep things as simple as possible. A direct connection between instrument and computer with no wider network connection seems sensible but it has some pitfalls.
- To connect your computer Ethernet port directly to the Instrument requires a special twisted cable. The cable used to connect your computer to a network hub will not work.
- If your computer uses a Dynamic IP Address then it cannot get an IP Address unless connected to a DHCP server. So in this arrangement won't work either.
- If the instrument uses a Dynamic IP Address it will not work unless your computer is configured as a DHCP server. Your computer will also need to perform the Name Server function to deal with such an instrument.
- Both computer and instrument will need to be on the same Subnet.
A direct connection is only easy if both computer and instrument use fixed IP Addresses on the same subnet and you have the correct cable.
Wider Network and Ping Utility
Using the wider network provides the servers needed for DHCP and Names. Once a Dynamic IP Address instrument is plugged into the network then it should be possible to find it via its Name and the Ping utility. If it is a fixed IP Address and it is plugged into the correct subnet it should again be possible to Ping it.
Ping is a test utility which sends a message to a defined port within your instrument. The instrument replies with a short data message. Virtually every unit on TCP/IP will support this action. If you cannot Ping your instrument you will not be able to talk to it.
Understanding TCP/IP and Data Logging
I have a question about the Microlink 851-SG: Strain Data Logger. How are the strain gauges connected to the datalogger? Do I need other elements to connect it to my laptop? How long can I measure with the device (1 sample/hour for example)?
The 851-SG comes with a connection box that has screw terminal connections to wire 2, 3 or 4-wire strain guages in quarter half or full bridge configurations. If you tell us how you will be using your guages, e.g. 120 ohm quarter bridge, then we will fit the necessary resistors to complete the bridge circuits inside the box. Then simply plug the box into to the analogue inputs connector of the Microlink 851 with the ribbon cable provided.
For long term logging you can setup the Microlink to log once per hour. You can use your laptop to read the logged data over an Ethernet connection. The Microlink can save up to 63000 sets of readings before overwriting data.
For more on the Microlink 851-SG see https://www.windmillsoft.com/daqshop/daq-usb.html.
For tips on making strain measurements see
Airdropping sensors from moths: Researchers use flying insects to drop sensors from air, land them safely on the ground
When a researcher sends a Bluetooth command, the sensor is released from its perch. Once on the ground, the sensor can collect data, such as temperature or humidity, for almost three years.
Source: University of Washington
New generation sensors are needed to prevent technological leaps being grounded before take-off, warn quantum expert
Sensor technology vital for critical national infrastructure is becoming outdated. The current weakness threatens anticipated advances, many involving quantum technologies, across different sectors - including climate change, defence, transportation, energy supplies and healthcare.
Source: Birmingham University
What if underwater robots could dock mid-mission to recharge and transfer data?
Robots can be amazing tools for environmental studies, but eventually they must return to a base to recharge their batteries and upload their data. That can be a challenge if the robot is an autonomous underwater vehicle exploring deep ocean waters.
Source: SCUBA News
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