PDS – Digital Sensors

Highly flexible and programmable digital sensor modules

» Posted on 16. May 2013

Related links:  Quick-Start | Commands | Programmer | Interfacing


 

Programmable Digital Sensors

 

The combination of an ACU2 module with different detectors, assembled into a M12 screw housing creates a rich set of small programmable digital sensors (PDSx), ready to be integrated in many environments.

In General there are two groups of PDSx modules:

 
  1. PDS modules with additional analog outputs for sensor and temperature values
  2. PDS modules with additional serial interface for digital chaining of modules

The electronic in both groups are the same. Due to limited number of output pins in a M12 housing, only 8 of 10 available signals can be routed to the output connector.This fact creates these two general groups of product families. One is focused on single sensor application per wired link offering both, the digital and the analog signals to the host. The other group of PDS modules gives the user the ability to chain several sensors on the same wired digital bus – monitoring the sample values of multiple sensors, but only in digital form.

When digital chaining is desired, there is no limit for the number of modules in a chain and how long the chain gets as long as the distance between two sequential modules doesn’t exceed 30 meters. The limitation in this scenario is the bandwidth. The digital signals are transmitted with 115200 baud over the wired bus. This is the maximum available bandwidth, which all  chained members have to share for transmitting their data to each other or to a gateway / host.

When analog modules are desired to be used, only one PDS module can be connected to each port of a host. One of the analog outputs is the conditioned sensor value and the other one can be a voltage in correlation to the sensor temperature or any other desired value controlled by the firmware inside the PDS module (user application programmable).

 

Features

 
  • Small form factor (M12 housing 65mm long)
  • Complete integrated sensor signal conditioning and processing
  • Including a 12-bit up to 200ksps ADC with scaleable dynamic range
  • Sensor sensitivities up to 4µV/LSB with auto gain capability
  • Temperature and noise compensation algorithms
  • Capable of storing sampled sensor data together with temperature and time stamps
  • Providing digital and analog sensor data on its 8 pin interface
  • Digital communication over RS-232 lines: sensor-to-sensor & sensor-to-host (PC)
  • Two independent RS-232 channels for chaining of sensors
  • Host independent intercommunication of sensors and actors in a chain
  • Possibility to port and integrate user applications

 

Latest PDS modules

PDS modules with sensors based on InGaAsx-InGaAsPbsPbSe or SiC materials are built by detectors from Laser Components in Germany. Due to a product based cooperation, Laser Components has all marketing and sales rights for this type of PDS modules.

Following PDS modules are available at Laser Components known as Digital Photodiode Sensors:

  Article #   Name   DPDS modules with digital & analog outputs
  3009081   C-MAJOR-4-1212-1.0-A   SiC Digital Photodiode 1.6mm²
  3009082   C-MAJOR-4-2525-1.0-A   SiC Digital Photodiode 5mm²
  3009083   C-MAJOR-4E-0505-1.0-A   SiC Digital Photodiode 0.5×0.5mm², eryth.
  3009085   C-MAJOR-4-1010-1.0-A   SiC Digital Photodiode 0.965mm², TO18
  3009086   D-MAJOR-17-3000-1.0-A   InGaAs Digital Photodiode, 3mm, 1.7µm
  3009087   D-MAJOR-17-1000-1.0-A   InGaAs Digital Photodiode, 1mm, 1.7µm
  3009088   E-MAJOR-22-1000-1.0-A   x-InGaAs Digital Photodiode, 1mm, 2.2µm
  3009089   E-MAJOR-26-1300-1.0-A   x-InGaAs Digital Photodiode, 1.3mm, 2.6µm

 

Brief Introduction

The PDS-series of modules are capable of sensing, conditioning, processing and storing sensor data without additional / external processing power. Results may be compared to user defined thresholds for generating digital messages to the environment, storing them inside the sensor itself or shift them out directly to a host via its RS-232 interface.

As shown in the following block diagram, PDS modules are generally built by an internal fixed temperature sensor and a programmable analog front end for interfacing various types of sensors. An integrated A/D converter and a 16-bit µController together with 4MB of Flash storage makes the PDS ideal for many applications in the industry.

 ACU2_block_diagram

Digital processing and interfacing of the module is based on a 16-bit RISC processor with 16 MIPS, 128kByte Flash and 10kByte SRAM. The ADC module is a 200ksps fast 12-bit SAR analog-to-digital convertor with reference generator for sensor biasing if needed.

Sampled sensor data can be transferred to a PC as raw data – to databases or custom applications – or as user friendly verbose characters to be displayed on a PC using a hyper terminal. Any PDS module accepts user commands to generate various types of data outputs needed by the user. Following picture shows transmitted sensor data to a PC by a PDS as voltage values and as a curve in addition.

 DPSlog_as_semi_graphical_curve

 

 

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