Multiplexer puts more into a PLC

Intech Instruments of Christchurch, New Zealand, has launched a multiplexer designed to make life easier for factory engineers struggling with a variety of inputs to a single PLC. The 2100-A16 is claimed to introduce a new era of intelligent data acquisition for PLCs, SCADA, PC chart recorders, and as a stand-alone multichannel datalogger. The newcomer provides an economical method of inputting a mixture of field signals into one PLC input or on to a PC chart recorder or SCADA.

Managing director, John Green, told Electronicstalk: 'Taking advantage of recent advances in hardware/software design, the 2100-A16 provides industry with a true multifunction station with flexible inputs and outputs'.

Inputs include 16 individually configurable analogue inputs and four digital on/off inputs.

Outputs include two analogue outputs and two alarm or control relay outputs.

Each of the 16 analogue inputs is individually configurable for most types and ranges of thermocouples, including Pt100 or Pt1000, mA, mV and V.

The communications port is available in RS232, RS422, RS485, and is used for configuration of the inputs/outputs, along with connecting to a SCADA, or MicroScan PC recorder, or for downloading data in datalogger applications.

One way of effecting PLC communication, Green said, is by using one analogue output from the multixplexer into the PLC, representing the 2100-A16 chosen input channel value.

The input channel is selected by one of two simple methods using PLC solid state or relay outputs.

Using clock and reset, the first PLC output momentary closes to clock the 2100-A16 to the next channel, and the second output resets the 2100-A16 back to channel 1.

Alternatively, four PLC outputs select the 2100-A16 channel required using a binary number.

This method is popular where some of the 2100-A16 input channels are in a PID loop, and need to be scanned more frequently than other channels, due to the ability to directly select the channel required.

Green adds: 'Several options are available for the CJC of inputs configured as thermocouple to give optimum accuracy and proving to be a valuable tool not only in industry, but in specialised testing applications such as aviation and laboratories'.

Other features of the New Zealand designed and manufactured multiplexer include: field calibration trimming of each channel to correct sensor inaccuracies; up to 16 integral on/off controllers; and control relay output expansion provided by the 16-way 2100-R relay expander.

Typical applications for this technology include: factory wide monitoring, cold storage temperatures, energy management, heat treatment, timber processing, food processing, and water/wastewater monitoring.