Use of barriers with Mantracourt ATEX amplifiers

An approved barrier must be used if the ALA5 or indeed any similar products are to be installed in a hazardous area (Zone 0)

The relevant parameters for the barrier are as follows:

  • Uo = 28V, Io = 100mA, Po = 0.7W, Barrier Impedance 300Ω.

These are maximum values, actual barrier parameters will vary from model to model however the barrier impedance is not permitted to change.

Two examples of suitable barriers are:

  1. MTL7706+ (passive Zener diode type with active current limit) manufactured by MTL Instruments
  2. KFD2-STC4-EX1/2 (3-way isolated type) manufactured by Pepperl and Fuchs.

The purpose of the barrier is to limit the amount of electrical energy that can be transferred into the hazardous area in the event of a fault condition thereby preventing the ignition of any flammable atmosphere that may be present.

Connection Details for the ALA5

A simple passive barrier is shown but this can be replaced by an isolated barrier such as the P+F KFD2 mentioned above. These devices prohibit ground loops which may affect measurement accuracy and stability by providing three-way isolation between power, input and output.

View the full specifications of the ALA5 ATEX load cell amplifier on our website.

Details on new resistance acquisition module

During the development of our new acquisition modules the measurement of tiny changes in resistance became key to get accurate readings and sensing small changes. In the creation of the temperature (T24-TA) and potentiometer (T24-RA) acquisition module we created two devices that sense a range of resistances. The T24-TA is designed to work with a PT100 sensor to accurately measure resistances from 20 to 250 Ohms, we provide an output in Ohms as a standard unit. The T24 wireless potentiometer acquisition module (T24-RA) is designed to measure potentiometers inputs between 500 and 100,000 Ohms. The standard wiring of the T24-RA is shown below in figure 1 connected to a potentiometer, figure 2 shows a potential divider circuit, R.ref is static known resistance and R.meas is the resistance under measurement. Using the custom calibration available in the T24-RA users can calibrate the output to whatever units they wish.

T24-RAView the full specifications of the T24-RA on our Mantracourt website.

7 things you need to know about the SGA

  1. The SGA load cell signal conditioner has a built-in Shunt Calibration function. Switch 8 of the Span switch, SW1 switches a 120k resistor in parallel with one arm of the bridge to produce a known shift in the Zero point. After calibration, switch in the Shunt Cal feature, note the change in output then switch it out. Use this figure to periodically check the integrity and calibration of the system. The PCB is configured to easily allow the Shunt Cal resistor to be changed to suit your application and load cell impedance.
  2. The Strain Gauge Amplifier can be set to provide 5V excitation as well as the normal 10V level – switch off SW4/8. As well as providing excitation for a strain gauge bridge, this can be useful for supplying power to an intelligent sensor (80mA maximum).
  3. An IS1224 module can be fitted to the SGA/D to isolate the bridge and electronics from the DC power supply. This module features a wide 9-36V power supply range making it suitable for automotive applications and other portable installations.Isolating the power supply will prevent ground loops and help minimise noise pick-up.
  4. The SGA load cell amplifier’s mA output can support both ‘sink’ and ‘source’ modes of operation. ‘Sink mode’ can control current flow either from the SGA’s own 15V supply, an external 5-50V DC supply or a suitable PLC input stage. In this mode neither output connection is common to the load cell. In ‘source mode’ the SGA load cell signal conditioner provides the current which flows through the external load to 0V. This mode has the advantage that the load cell’s  ‘EXC -‘, the SGA’s ‘Output -‘ and the power supply negative are all commoned together.
  5. The SGA has a built-in low pass filter adjustable from 1Hz to 5kHz to reduce noise or the effects of vibration in the measurements.
  6. The Strain Gauge Amplifier can support high impedance strain gauges such as pressure transducers. Its 0.1 to 30mV/V input range makes it suitable for a wide variety of applications.
  7. J2, the load cell connector provides a reference voltage of 2.5V or 5V depending on whether the excitation is set to 5V or 10V. Connect a mV source between this point and ‘+Strain Input’ to facilitate calibration from the load cell manufacturer’s published figures.

View the full specifications of the SGA on our Mantracourt website.

New Software for USB Strain Gauge/Load Cell DSCUSB

We’ve made some small changes to the software of our DSCUSB strain gauge to USB converter in response to a suggestion from one of our Partners in the USA.

Before, interested users could only view one static page of the software if the device wasn’t connected. This hid away all the helpful functions of the toolkit.

Now, even if the device isn’t connected, a DEMO mode can still be viewed so users can see all of the useful software pages such as the applying two point calibration, adjusting the measurement rates and filters, logging to .csv, and saving and restoring. This will help to show what a comprehensive device the DSCUSB can be.

Download the software to view the DEMO mode here

Wireless Telemetry Relay Module for Mains Power Switching

Capable of main power switchingT24-RM1 Wireless Telemetry Relay module offers dual 5 amp relays capable of mains power switching. These relays can be configured as high, low or window alarms to one or a sum of up to 8 x radio telemetry T24 devices. The relays can be latched and a volt free input or external command can be used to reset them. An alarm signal relay is also on board and operates if communications are lost with input devices or other selectable errors occur. This alarm relay can be silenced by a volt free input.

The T24-RM1 has many application possibilities when used as part of a system with other T24 devices from Mantracourt’s wireless telemetry range. The relay could be used to switch on a claxon siren, flashing beacon, control valve or motor.

An example case might be in the use of a crane load system where a single load cell with a wireless telemetry T24-SA Strain Acquisition Module embedded within the load cell transmits back to the T24-RM1 to warn of an approaching overload – the T24-RM1 switches a relay to sound a siren. Similarly, a warning system for a silo could be configured using 4 x wireless load cells that the T24-RM1 sums and compares to a value, which in turn switches and sounds an alarm.

The T24-RM1 could also be used for simple batch weighing systems. The weight of a vessel could be monitored using wireless load cells containing a T24-SA strain gauge to telemetry converter. When the vessels weight is under a specific value, a feeder valve should be open. Once the load in the vessel goes beyond the user limit the valve is shut and the batch is weighed.

The T24-RM1 benefits from having two relays which, if wired together appropriately, can be used to provide a windowed alarm system where the sum of up to 8 x devices can be used to sound an alarm if the total goes above or below user defined limits.

The applications for the wireless relay module are broad and multiple relays can be used to build up many controls systems. With open field wireless range of up to 200m, the T24 wireless telemetry range offers an alternative to wired systems.

Handheld Strain Gauge Indicator with RS232 Interface

Mantracourt’s PSD portable strain display or load cell indicator has been used for many years by companies worldwide as a simple wired solution for monitoring the output from load cells.

A lesser known relative is the PSD RS232 version which enables the handheld indicator to connect to any RS232 interface whether it’s a PC or simple data logger.Recording data from a load cell to RS232 via the PSD Handheld Strain Gauge Indicator

The PSD232 sends the displayed value to the RS232 port at 9600 baud in an ASCII format, terminated by a carriage return and line-feed making it suitable for stand alone data loggers, larger serial displays as well as interfacing onto a PC for logging which can provide a useful record during a calibration or load cell test.

The RS232 output is provided at the same time that the display is updated which depends on how the PSD has been set up by users. Updates rate of up 10Hz can be set.

For more information, view the specification of the PSD232 strain gauge display.

Digital Strain Gauge Conditioner (DSC) Identification Software Upgrade

Digital Strain Gauge Conditioner Utility Software

Digital Strain Gauge Conditioner Utility Software

The Identification Utility software for Mantracourt’s Digital Strain Gauge Converter has undergone improvements and now offers a faster and more robust utility for DSC and DCell users.

Version 1.4 of the application will detect a DCell or DSC connected to a PC when the station number or the baudrate is unknown or has been inadvertently changed. You will need to know the protocol to save trying each type. Protocols are MantraBus, MantraASCII and ModBus.

To start using the application, download here:

http://www.mantracourt.co.uk/software/identify-unknown-dcell-or-dsc

Connecting to T24 Telemetry Modules Without Removing Power – New Feature

News for our T24 users. An enhanced feature has been added to Mantracourt’s T24 Toolkit to help with pairing if you’re unable to physically reach the T24 module. Previously, configuration could only happen by removing and re-applying power. Now with the new version of T24-Toolkit you can connect and configure your device wirelessly provided you know its Radio ID and Data Tag.

Take a look at the Toolkit screenshot below and you will see below the “Pair” button there is a highlighted link that can take you to the new connection functions. Follow the link to the advanced module access page where there are two options to connect:

1. Safe Mode: To be used on any firmware version of the T24-Acquisition modules, this method may not work every time as it can be influenced by large amounts of radio traffic or if the device is transmitting at a very low rate.

2. Full Mode: This method is to be used with T24 devices with firmware version 1.06 and above. The method both wakes and pauses the device simultaneously.

How to pair to your T24 telemetry acquisition without removing power

Be aware when using either of these functions it is essential that the user return to the home page of the toolkit which sets the acquisition module back into its normal running mode. If a user moves out of range of the device it could be left paused and will need to be reconnected to and reset by returning to the home page while connected. If your device is not reset after configuration, the toolkit will alert you while navigating back to the home page.

Click here to download the latest T24 Toolkit software to access the new feature.

We strongly advise that if using either of these methods that the acquisition module is tested to ensure it is working as expected afterwards.

Welcome and thanks for listening

Welcome to the first blog entry on Mantracourt’s blog site.

We’ve been watching and reading blogs in the industrial market place over the years and when we decided to launch this space we felt that it would be an ideal place for technical discussions on the range of products we design and manufacture – a space where our engineers can give insights and tips – and where our customers and product users can leave comments and suggestions.

We’ll be posting regular articles on different products in our standard product range, the first one looks at how our digital strain cards can be used to create a weigh bridge using the DSJ1 and 4 enclosure along with a digital display. Those of you who receive our email newsletters will recognise some of these posts.

We really hope these posts will be interesting and informative to new and existing customers.

Please feel free to leave comments – we actively encourage you to. Thanks for listening.

Create Weigh Bridge with Digital Strain Cards

A simple weigh bridge can be created using Mantracourt’s DSC (Digital Strain Cards). DSC’s can be housed individually, in a DSJ1, or in sets of four in a DSJ4. Both of these enclosures are simple junction boxes that have screw field terminal connectors for load cell input, Power and RS485 interface. Up to 8 DSC can be connected to a DS485DIS.

In this example 4 separate DSC’s are housed individually in DSJ1’s and connected together in ‘Daisy Chain’ using a 4 core cable back to the DS485DIS serial display.

The DS485 display allows the user to view the total weight on all four platforms as well as being able to view the individual platform weights. The total weight can be toggled between gross and a zeroed net display using the keypad.

The advantage of using RS485 and individually housing each DSC is that the weigh platforms can be spaced far apart with no loss of accuracy in measurement due to the long load cell cables – the RS485 bus carries the distance. The total length of the RS485 cable can run up to a 1000m.

The overall system can be configured and calibrated using Instrument Explorer over the RS485 interface.