Now with the Open Source One-Cable-Technology BiSS LINE

MULTITURN KIT ENCODERS WITH BISS LINE INTERFACE

kit_encoder_biss_line

Now with the Open Source One-Cable-Technology BiSS LINE

POSITAL’s new family of kit encoders provide the manufacturers of motors and other machinery with rugged, accurate and cost-efficient tools for building rotary position feedback into their products. The new kit encoders are based on POSITAL’s highly successful self-contained magnetic rotary encoders. Now however, the core components of these instruments are available as separate assemblies that can be readily integrated into other products.

  • Asynchronous RS485 Interface, 4-Wire Configuration
  • Open Standard: BiSS Line
  • Smart Multiturn – Wiegand Technology – No Battery, No Gear!
  • Compact Single PCB Design
  • Auto-Calibration – No Mechanical Adjustment
  • Insensitive to Dust and Moisture

Non-Proprietary Interfaces Reduce Costs, Increase Versatility

The electronic interface for these encoders is based on non-proprietary BiSS Line and BiSS-C communications standards . Unlike proprietary, vendor-specific interfaces, these open-source standards are be supported by many manufacturers of sensors and motion controllers, freeing users from a “locked-in” relationship with a single supplier. Standard 4-wire RS485 connections are supported, so that motor manufacturers who adopt POSITAL kit encoders can often make use of existing connectors and cables. IP core software is available for FPGAs widely used in motion controllers. This reduces the development effort required to make use of BiSS communications technologies.

The BiSS Line standards also support a single cable approach to motor connections, with power and control wires combined in a single cable. Point-to-point or multi-slave network configurations are supported, simplifying wiring layouts in complex machines.

High Performance with Low Maintenance

The POSITAL kit encoder components offer advantages for motor and rotating equipment control feedback. Compared to analog resolvers, they provide improved accuracy and multiturn measurement capabilities. Their output is digital, which avoids the need for A/D converters in the control system. Compared to optical disk encoders, POSITAL’s magnetic encoders are less costly, less vulnerable to contamination from oil or dust and more resistant to shock and vibration. Multiturn absolute position measuring capability is based on an electronic rotation counter powered by the company’s well-proven Wiegand-effect energy harvesting technology . This system is self-powered, so rotation counts are always accurate, even if rotations occur when there is no control system power available. With no need for backup batteries and no need for periodic backup battery checks and replacements, maintenance requirements are significantly reduced.

Efficient Installation

POSITAL magnetic kit encoders are easy to incorporate into normal manufacturing processes since they don’t require near-cleanroom assembly conditions. A built-in self-calibration capability can be used to compensate for small sensor-to-shaft alignment errors occurring during assembly. The electronic components, including Hall-effect sensors, a 32-bit microprocessor and the Wiegand-wire energy harvesting system, are packaged in a convenient 36 mm diameter, 24.2mm deep unit. For servomotors with magnetic brakes, a special magnetic shield can be installed to isolate the magnetic pickups from external magnetic fields.

The resolution of the new POSITAL kit encoders is 17 bit, with an accuracy of better than +0.1°. The operating temperature range is -40 to +105 °C.

Reference: click here.

D&D Engineering – “W’ere YOUR Sensor Guys”
3835 E. Thousand Oaks Blvd. Suite 464 Westlake Village, CA 91362  – Voice: (818) 772-8720 Fax: (818) 772-2477 Toll Free: (888) 333-6474
Email: sales@sensorguys.com Website: www.sensorguys.com

New Organization promotes No-Charge, Open Source Interface Technology for Industrial Control Systems

POSITAL PARTICIPATES IN LAUNCH OF BISS ASSOCIATION

biss_association

New Organization promotes No-Charge, Open Source Interface Technology for Industrial Control Systems

POSITAL FRABA has announced that it is participating as a founding member of the BiSS Association e.V. , a new organization dedicated to encouraging the use of the BiSS family of open-source industrial communications protocols.

BiSS communications protocols were developed by the German company iC-Haus GmbH as an efficient and feature-rich digital interface for communications between industrial sensors, actuators and control devices. iC-Haus is also the source of ASIC chips that support the implementation of this interface in industrial devices such as sensors, actuators and controllers.

Features of the New BiSS Interface

The BiSS interface is hardware compatible with the well-established SSI (Serial Synchronous Interface) digital interface, but offers significant enhancements. BiSS supports continuous (real-time) communications between controllers and sensors. BiSS Safety offers functionality for critical systems where safety ratings up to SIL 3 are required. Applications of the BiSS interface include manufacturing robotics, motor feedback, servo drives & motion control, position encoders and CNC drives.

An important new development is BiSS Line – an implementation of BiSS protocols that can be deployed in a single cable configuration and features forward error correction (FEC). This makes BiSS Line an ideal interface for servomotors where the single cable feature offers a significant reduction in wiring system complexity.

BiSS is offered as an open source interface. There are no licensing fees for either manufacturers of BiSS-enabled devices or their customers. BiSS Association e.V. is autorized to grant free-of-charge BiSS licenses to device manufacturers and BiSS users. The agreement defines rights and duties to make use of associated patents and trademarks for BiSS held by iC-Haus.

New BiSS Association Organization

The new BiSS Association organization aims to expand the use of BiSS technology throughout the world. It will also provide a communications platform for technical standards and cooperative marketing initiatives. POSITAL FRABA’S Jörg Paulus has been appointed Vice Chairman of the association, joining Dr. Heiner Flocke of iC-Haus (Chairman) and Alexander Ehnert of Hengstler GmbH (Treasurer). Membership in the BiSS Association is open to all companies and institutions. Members can participate in the development and promotion of this exciting new interface. Access to BiSS technologies and licensing arrangements are open to members and non-members alike.

Reference: click here.

D&D Engineering – “W’ere YOUR Sensor Guys”
3835 E. Thousand Oaks Blvd. Suite 464 Westlake Village, CA 91362  – Voice: (818) 772-8720 Fax: (818) 772-2477 Toll Free: (888) 333-6474
Email: sales@sensorguys.com Website: www.sensorguys.com

Smartec NEW Laser Solder Service 

NEW  Laser Solder Service

Often people ask us how to solder thin wires to the HEC, the SMT172  hybrid element (2.5 x 8 mm) and also to SOT223 a housing special designed for Surface Mount Technology but also used as sensor housing. In case the SOT223 is mounted on a PCB the temperature of the PCB is given and not the temperature of surrounding (suppose you don’t want that).

Afbeelding met elektronica Beschrijving is gegenereerd met hoge betrouwbaarheid

Therefore soldering wires (30AWG)  to the SOT223 is an option.

For both the housings we have designed a little laser solder station to solder the wires on without damaging the sensor by high solder iron temperature.

Reference: click here.

D&D Engineering – “W’ere YOUR Sensor Guys”
3835 E. Thousand Oaks Blvd. Suite 464 Westlake Village, CA 91362  – Voice: (818) 772-8720 Fax: (818) 772-2477 Toll Free: (888) 333-6474
Email: sales@sensorguys.com Website: www.sensorguys.com

Customizing mass flow and pressure controllers: brilliant to baroque

Customizing mass flow and pressure controllers: brilliant to baroque

Posted by: Dan Yount

Many customers, even our most loyal ones, don’t realize that we customize just about EVERY Alicat instrument order. That’s because all our instruments are built when you order, and configured and programmed to best suit the application and conditions for which you’re buying them. Customizations can range from having a meter automatically tare itself every 24 hours, to engineering new limits of what our pressure controllers can handle! To give you an idea of how we work out your new requests, here are some simple and helpful customizations we produced on request.

Local Valve Drive Percentage

Resulting from a customization created at a customer’s request, the Local Valve Drive (LVD) option lets you monitor the work your valve is doing—because it can help you assess whether your process is in trouble. The LVD parameter appears on the large, multivariate display screen of an Alicat mass flow controller (or pressure controller), right above the main parameter output in the center. The LVD option reports the proportion of power being applied to the valve to maintain the setpoint. Valve drive percentage is something our devices normally track internally, and is a useful data point in troubleshooting, should you ever need it (our free lifetime support, available by phone or email, can help you with any troubleshooting you need). The value to the customer is that it serves as an indicator of the overall health of their chemical reactor vessel’s inputs and outputs. A significant change in the valve drive may indicate several possible failure conditions. Here’s a quick video showing this simple and smart customization at work:

Our “Local Valve Drive” (LVD) customization allows you to see how much drive is being given to a valve from your controller. One of our customers wanted a quick way to diagnose if their reactor’s output was dropping. Given steady pressures and flow rates, the valve drive will consistently be within a certain range. Our customer knew that at 30 PSIG inlet pressure with 10 SLPM of flow, the valve driver would be somewhere between 35-40% full power typically. If they saw the valve drive creeping much higher than this, then they would know that they were losing pressure differential in the process, since the valve was needing to open the valve wider than usual to create the same amount of flow. It may be that something is clogging the valve, making it open wider to allow flow to pass through. If they saw the valve drive percentage at 100 this would indicate that the valve was 100% open, or it was at least trying to be that way. They’d know that their reactors were creating such little output that it wasn’t possible to generate enough flow to satisfy their setpoint.

Local Valve Drive is now an option you can ask for, if your application calls for it.

Controlling pressurization speed

A customer wanted to use a pressure controller to maintain a certain pressure within a leak test chamber. However, they also wanted to make sure that the chamber would not pressurize too quickly.

MCD-Series bidirectional mass flow controller, shown with IPC option

MCD-Series bidirectional mass flow controller, shown with IPC option

To assure this, we built them a dual-valve mass flow controller in our MCD Series. A dual-valve mass flow controller can be programmed to fill with one valve and vent with a second valve. Like all our standard MFCs, it can be set to control flow based on pressure, rather than mass flow, (while still measuring mass flow!) Our dual-valve mass flow controller is also able to measure mass flowed in either direction. The MCD series of mass flow controller can be perfect for dispensing gases into a closed volume without overshooting or overpressurizing, or as an instantaneous pressurized leak test, with a built-in pressure relief valve for quickly changing the devices under test.

The customer used pressure control mode so that the setpoint was in pressure units, not mass flow units.

Finally, we created a custom software feature: a “Mass Flow Limit” function, configurable through the front screen. This would operate as a governor on the flow rate. It tells the valve to not open any further, once a certain mass flow rate was reached. This effectively limited how quickly the unit was allowed to pressurize their system.

Custom Configuring: a Stainless, IP-rated Dual Valve Pressure Controller

Customization can come in the form of unique combinations of options. Like this PCDS–it’s a dual valve pressure controller with a lot of options added on:

psds-ip65-remotevalve_lr

  • Stainless flow bodies and corrosion-resistant seals for using aggressive gases
  • A remote pressure sensor port (it’s on the backside of the flow body with the display), so that the pressure control will be based on a remote volume, independent of the valve lines.
  • IP-65, a liquid ingress prevention rating, means all the connectors are sealed with gaskets, and the display panel doesn’t have our menu buttons
  • The second valve is remote. The cable is the right length to mount the “relief” valve in a different location of the process flow.
  • Modbus industrial protocol on board. Without interface buttons to program the device, remote commands are necessary. But the display will provide a visual confirmation of the operation of the device for any technicians on the scene.

Altogether, it’s a very unusual device.

What’s your application?

When you place an order, our apps engineers always ask a lot of questions, like “What is the application? What are the operational parameters, and what are you trying to do?” This guides them in recommending things like custom tuning of valves (no extra charge!), or the selection of a particular sensor, or communications options. We do our best to make the device perform at its very best in your hands. Sometimes that means custom engineering, sometimes just custom configuring of existing options. Alicat prides ourselves in our ability to accommodate many custom configurations, or invent a solution!

Reference: click here.

D&D Engineering – “W’ere YOUR Sensor Guys”
3835 E. Thousand Oaks Blvd. Suite 464 Westlake Village, CA 91362  – Voice: (818) 772-8720 Fax: (818) 772-2477 Toll Free: (888) 333-6474
Email: sales@sensorguys.com Website: www.sensorguys.com

SMT172 to I²C Interface Board

Function: I²C Interface and Conversion from SMT172 to SMT160-30 Temperature sensor output

Introduction

Regularly Smartec is asked for a temperature sensor with an I2C output. Because of the low power consumption of the SMT172 sensor itself, the self heating of the sensor is negligible, which contributes to its precision. An on chip integrated I2C interface would produce too much heat. The only way to preserve the sensors precision and still have an I2C interface, is to combine them on a tiny pcb. This board also does the calculations on the sampled duty-cycle and converts the result in ASCII data with an accuracy in the range of mK.

The board can be used in PWM mode (instead of I2C mode), to meet compatibility requirements with some existing (obsolete) SMT160-30 applications.

The output signal

The output signal is a standard compatible I2C signal (slave) and the standard address is 111 (0x6F). A secondary address (7 bits) with the default value of 115 (0x73) is available. The value of this secondary address can be changed by the user. This process will be explained below.

Highlights

  • Accurate measurement in full SMT172 temperature range
  • Measures the output of the SMT172 in 0.001 °C steps
  • Both I2C and PWM (SMT16030 like) output
  • Board temperature range 0 – 75 °C
  • Programmable secondary address, allowing for multiple sensors with interfaces on the same I2C bus
  • 3.3 V. regulator for powering the SMT172
  • Powered by the I2C bus itself
  • Can be used for all housings of the SMT172

PDF: SMT172TOIIC.

D&D Engineering – “W’ere YOUR Sensor Guys”
3835 E. Thousand Oaks Blvd. Suite 464 Westlake Village, CA 91362  – Voice: (818) 772-8720 Fax: (818) 772-2477 Toll Free: (888) 333-6474
Email: sales@sensorguys.com Website: www.sensorguys.com

How can I take advantage of PID Tuning?

How can I take advantage of PID Tuning?

Posted by: Jas Gill

Alicat flow and pressure controllers use closed loop control algorithms to achieve their highest degree of control stability. The algorithms are a mathematical relationship that dictates the response of the valve to the flow or pressure conditions. It assesses the difference between the set point and the process value—whether it be mass flow, volumetric flow, or pressure—as an error. The degree of error determines what kind of input to send to the valve, reaching the correct value in the quickest time possible. The amount of time expended to minimize the error—and therefore the control response of the controller—depends on what type of loop is being used (PD or PD2I) and what P, D and I values are used.

When you order your controller, we set the Proportional and Derivative values by trying to replicate the application parameters (process conditions) to the best of our ability before we ship it to you. This customization to your system is one reason our controllers are fast.

No worries

If process conditions change, the valve response may change drastically depending on how much you deviate from the conditions the valve was tuned at. You need not worry about erratic response from your controller if the conditions change, since PID tuning can be done in field to get better control at the new process conditions. You can change PID terms through the display panel buttons, or through electronic commands using digital or analog communications.

You’ll get optimal performance from your controller when you select correct values for all three parameters (two in case of single valve controllers). The ‘P’ term opens the valve to achieve the set point, ‘D’ term applies a damping influence to eliminate the overshoot and ‘I’ function helps the system settle to the set point.

A previous blog describes the P, D, I terms:
Achieving Responsive and Stable Valve Control with PID Tuning
Briefly:

  1. Proportional (P): The P term applies power to the valve as it tries to decrease the error between the set point and the process value position to achieve the set point.
  2. Derivative (D): Think of this as a damping term which tries to reduce the rate of change. The larger the D term, higher the damping influence on the valve drive.
  3. Integral (I): Integral in calculus is the area under the curve, it determines the output of the valve as a function of the sum of all the errors. I term takes into account previous readings to reduce the error and correct the process value to the set point.

 

Oscillating around the set point

If your controller shows signs of oscillations about the set point, or is unstable in its control response, it is a sign that the P term is too large. The greater the P value, the greater the range of oscillation. To get rid of the oscillation (settle the controller to set point), you would need to decrease the P term.

Let’s say you have a 10 SLPM controller set to 10 SLPM for Hydrogen. The controller is oscillating between 8 and 12 SLPM. Hydrogen is a low viscosity and a very light gas compared to Air. This being the case, the valve—which is tuned with air—should be re-tuned. So, starting with the factory P value (for example, it may be 1000), try decrements of 10% and keep on going down until you see the controller settle to the set point quickest. Generally, we only touch the D terms after you have altered the P term, so if you still have small oscillations, you can increase the D value with 5-10% increment. This should help the controller become more stable.

PID response shown graphically, by varying P

Excessive P (purple) produces oscillation. Low P (red) slowly rises to the setpoint. Optimal (green) settles quickly.

Delayed setpoint

A second situation is when your controller takes too long to get to the set point or never achieves the set point, but settles to a flow rate or pressure below the set point value. This implies either too small a P value being used or too large a damping influence. Using the analogy of a car, imagine you want to get to 70 miles per hour. but when you start increasing the speed, someone applies brakes which decreases the acceleration of the car. The car may never get to 70 mph if the deceleration is larger than acceleration, and the car may settle at a speed of 60 mph when acceleration = deceleration, or the opposite forces are equal.

In this case, try increasing your P value in 10-15% increments until you see the controller getting close to your set point. Next step would be to decrease the D value to help the controller get to the set point in a quicker time. If you start seeing some oscillations, that means the D value has been set too low.

Control loop adjustment is all about getting a good feel of how the controller responds to changes in the P and D terms. The gas viscosity, inlet pressure, back pressure can greatly influence how the valve responds. Tuning the valve is an art rather than science and the more familiar you get with your controller, the better you’ll be able to tune it.

 

 

 

 

Reference: click here.

D&D Engineering – “W’ere YOUR Sensor Guys”
3835 E. Thousand Oaks Blvd. Suite 464 Westlake Village, CA 91362  – Voice: (818) 772-8720 Fax: (818) 772-2477 Toll Free: (888) 333-6474
Email: sales@sensorguys.com Website: www.sensorguys.com

Alicat Mass Flow Controllers Powers MDC’s XpressStick Gas Delivery Module

Alicat Mass Flow Controllers Powers MDC’s XpressStick Gas Delivery Module

Posted by: Edgar Schrock

Gas connection module benefits from Alicat’s MCE’s high precision flow control

Alicat Scientific’s MCE mass flow controllers have been integrated into MDC Vacuum Products’ XpressStick™ MFC Gas Stick. With precision control of gas flows of up to 20SLPM and onboard display, Alicat’s MCE provides gas programming functionality to the gas connection module, which links pressurized gas inputs to vacuum chambers.

The Alicat MCE accurately controls gas flow rates as low as 0-0.5 sccm full scale or as high as 0-20 slpm full scale. With 20 to 50 millisecond control response times to setpoint changes, the MCE improves vacuum coating end products and helps eliminate target poisoning.

The MCE mass flow controller helps drive precise doses of gases for mixing and purging in vacuum coating systems

The all-in-one design of the XpressStick MFC gas stick eliminates complex hardware specification in processes which include a combination of specialty gases, pressure, precise regulation, and vacuum. Its easy programming and precise gas control system allows users to go from bottle to process in one simple step. Designed to meet ultra-high purity process requirements, the XpressStick is also offered in a stainless steel model for corrosive environments.

With the MCE’s zero warm up time, the XpressStick is ready to control process flows in just one second, with real time mass flow, volumetric flow, absolute pressure and temperature data, fully compensated for temperature and pressure. The gas module is programmed directly through the MCE’s integrated display, with easy changes to gas type using the on-board gas calibrations.

“Fast response time, accuracy, and reliability were all key criteria in choosing an MFC instrument for our XpressStick,” explained MDC Vice President of Engineering & Technology, James Moore. “Based on past experience with Alicat, we knew that they could deliver all three, with an integrated display that enables our all-in-one design.”

Alicat mass flow controllers, pressure controllers and vacuum controllers are used in vacuum coating systems around the world.

Reference: click here.

D&D Engineering – “W’ere YOUR Sensor Guys”
3835 E. Thousand Oaks Blvd. Suite 464 Westlake Village, CA 91362  – Voice: (818) 772-8720 Fax: (818) 772-2477 Toll Free: (888) 333-6474
Email: sales@sensorguys.com Website: www.sensorguys.com

Multiplexer

The MUXC01 multiplexer  is specifically designed to work with the Smartec Universal Transducer Interface (UTI). The combination of the UTI and the MUXC01 makes it possible to measure multiple capacitances with a very low capacitance value and a very high accuracy (15 bits).

The number of capacitor being measured can be increased by cascading the multiplexers, Each multiplexer contains a 9 bit shift register and can measure 9 capacitors. As the capacitance measurement is based on charge transport, special attention is given to the outputs of the circuit. Through careful design, the multiplexer has an output impedance of less than 20 Ohms and the rail-to-rail output voltage is well defined.

These features make the combination of the UTI and the MUX C01 multiplexer the best solution for measuring  multiple capacitances.  By constructing arrays, each possible capacitance structure can be measured easily and accurately. The device is available in DIL or SOIC package and as bare die.

Reference: click here.

D&D Engineering – “W’ere YOUR Sensor Guys”
3835 E. Thousand Oaks Blvd. Suite 464 Westlake Village, CA 91362  – Voice: (818) 772-8720 Fax: (818) 772-2477 Toll Free: (888) 333-6474
Email: sales@sensorguys.com Website: www.sensorguys.com

SMT172 connected to Raspberry Pi via I2C

Introduction

Regularly Smartec is asked for a temperature sensor with an I2C output. Because of the low power consumption of the SMT172 sensor itself, the self heating of the sensor is negligible, which contributes to its precision. An on chip integrated I2C interface would produce too much heat. The only way to preserve the sensors precision and still have an I2C interface, is to combine them on a tiny pcb. This board also does the calculations on the sampled duty-cycle and converts the result in ASCII data with an accuracy in the range of mK.

The board can be used in PWM mode (instead of I2C mode), to meet compatibility requirements with some existing (obsolete) SMT160-30 applications.

Highlights

  • Accurate measurement in full SMT172 temperature range
  • Measures the output of the SMT172 in 0.001 °C steps
  • Both I2C and PWM (SMT16030 like) output
  • Board temperature range 0 – 75 °C
  • Programmable secondary address, allowing for multiple sensors with interfaces on the same I2C bus
  • 3.3 V. regulator for powering the SMT172
  • Powered by the I2C bus itself
  • Can be used for all housings of the SMT172View or download SMT172TOIIC.pdf , click here.

Reference: click here.

D&D Engineering – “W’ere YOUR Sensor Guys”
3835 E. Thousand Oaks Blvd. Suite 464 Westlake Village, CA 91362  – Voice: (818) 772-8720 Fax: (818) 772-2477 Toll Free: (888) 333-6474
Email: sales@sensorguys.com Website: www.sensorguys.com

Kits and Modules

We have developed a few modules that make designer’s lives easier and show off the great features of our sensors. Some of these boards are being used in measurement and production environments due to their ease of installation and the high quality of the outputs.

For the temperature sensors we offer the SMTAS04 and SMTAS08 boards. These boards can be connected to any PC using a USB cable – no extra power supply needed! These boards have high accuracy and great resolution (0.01C).

We have also developed a new UTI evaluation board; the UTI Evaluation Kit USB. This board is a real “plug and play” system. Very accurate capacitance and resistance values can be measured. Porting the very low output voltages of infrared sensors to other equipment is very challenging so we have designed an IIC interface module and USB module that make this very easy.

Reference: click here.

D&D Engineering – “W’ere YOUR Sensor Guys”
3835 E. Thousand Oaks Blvd. Suite 464 Westlake Village, CA 91362  – Voice: (818) 772-8720 Fax: (818) 772-2477 Toll Free: (888) 333-6474
Email: sales@sensorguys.com Website: www.sensorguys.com