The SMW surface mount intelligent strain gauge amplifier and weighing controller, available from Celsum Technologies, is a rugged, compact microprocessor based unit specifically designed for weighing operations using strain-gauge based load cell weighing sensors.
Its flexibility of design allows for the connection of most load cells, pressure or strain gauges over a wide range of sensitivities.
With an eight-digit 12.7mm LCD, and housed in a light grey ABS case, the SMW is sealed to IP65 standard to meet most environmental conditions, or as a DIN rail mounting module with a separate stainless steel panel mounting display and keypad.
The strain bridge circuit has an excitation voltage of 10V with a capacity of 160mA, sufficient to handle up to six 350ohm load cells in parallel.
The working units may be set as engineering units, and communication with intelligent hosts is possible via the ASCII, Modbus and Mantrabus protocol options.
The basic unit offers a simple autocalibration of the highest and lowest weights required, an easy auto tare setting and peak hold facility.
A password facility gives protection to setup parameters.
DC analogue outputs of 4-20mA and 0-10V are standard with full scaling over any desired range and the ability to invert these outputs if required.
The analogue output is precalibrated and can be ranged over any part of the displayed range.
Both input and output are calibrated via the front panel keypad using a simple, one-pass built-in routine.
Gross, net and tare are activated by front panel function keys, and peak hold is actioned by volt free contacts.
Gain sensitivity is selectable via DIL switches between 0.5 and 200mV/V.
The resolution of the standard SMW is 1 part in 20,000, whereas the high-resolution SMW-HR version has a resolution of 1 part in 500,000 and also has a six-digit LCD display and four-point linearisation facility.
Several "plug in" options are available.
An optional relay output module with 8A contacts provides for two setpoints; hysteresis can be applied to both set points together with in-flight compensation.
Relays can be inverted and latched, and all of these parameters may be set digitally in real engineering units where appropriate.
Both relay and analogue outputs have a high level of isolation.
Optional communications modules provide for 20mA noise-immune current loop, RS232 or RS485 connections to a PC, PLC or main frame.
This allows for the input variable to be viewed and any setup parameters changed.
Multiple 20mA SMWs can be connected via an IF25 current loop to RS232 interface which, when included, allows for an expansion of up to 250 SMWs.
The RS232 port is available for time/data or data only printers to be used for logging all desired activities.
Baud speeds between 300 and 19,200 are selectable.
Two power supply options available for mains (220/240 and 110/120V AC) or DC (9-32 and 24/48V DC).
Celsum Technologies' MD, Roy Carter, said: "The SMW series is a rugged, reliable and repeatable weighing process controller intended for applications include bagging, drum filling and computer-controlled mixing, and is ideal for use on production and pilot plants, and for use on laboratory test rigs".
The SMW and SMW-HR are complementary to the SMP process weighing controller, and to the other instruments offered by Celsum Technologies for measurement, signal conditioning and weiging process control.