Signal Conditioning
Wieland's ASV modules are measuring amplifiers that convert temperature measurements from a PT-100 resistor to analog outputs. The PT-100 resistor, which is not supplied with the module, has a resistance of exactly 100 ohms at 0°l C. Several input ranges are available, e.g. 0-100, 0-300, and 0-500° (contact the factory for other standard ranges available). Analog outputs available are 0-10V, 0-20mA, and 4-20mA. The ASV modules are available in two version, 3-wire and 4-wire. For those using 2-wire PT-100 sensors a 3-wire can be easily incorporated by simply jumpering the differential voltage lines on the available leg.
Type AKB and AKT
Wieland coupling modules are used to convert an analog measurement from one signal standard to another. The AKB module provides the conversion without the provision for electrical isolation between the inputs and outputs or from the power supply. The AKT module, on the other hand, does supply 3-way isolation; that is to say, isolation between the input and the output and isolation between the power supply and the input and the output. Several reasons for using signal conversion modules are:
•Signal inputs from devices such as PLC's can be linked to signal sources having another signal standard
•Current signals can be used for long lines, although the device connected requires a voltage source
•Various signal sources can be converted to a uniform internal signal level
Available input/output ranges include 0-10V, 0-20mA, and 4-20mA. Contact the factory for other standards.
Type ADW and DAW
Wieland's ADW modules are used for the conversion of analog signals to digital, and the DAW modules are used for the conversion of digital signals into an analog form. The modules are available in both an 8-bit and a 12-bit version for higher resolution. When attached to some type of controller, typically a PLC, the signals are activated via a hold pin. With the analog to digital module the outputs are normally not active. When the hold bit is switched to high however, the ADW carries out an active conversion and the digital signal is passed. With the digital to analog module the signals are transparent with the hold bit low. When the hold bit is switched high the last value stored is carried through. Available analog inputs with the ADW are 0-10V, ±10V, 0-20mA, and 4-20mA. Available analog outputs with the DAW are 0-10V, ±10V, and 0-20mA.
Type UET and UET-P
The UET and UET-P modules serve, depending on equipment, to generate switching points dependent on user-set threshold values and to display the measuring value at any given time. The switching points are set via two potentiometers on the outside edge of the module. The switching outputs become active when the monitored analog values exceed or fall below the limiting values set with the potentiometers. The UET-P version of these modules provide the switching via two isolated relay contacts. Both modules are available with either a LCD display to monitor the analog signals, or with measuring pins that must be accessed with an ammeter.
Type CSR
Wieland's CSR module is very similar to the UET modules in that it provides a single switching threshold value for the user to monitor processes. The input to the CSR is limited to 4-20mA. The output is supplied with a SPDT relay for process control.
Wieland Inc., 49 International Road, Burgaw, NC 28425. Tel: 910-259-5050; Fax: 910-259-3691.