MicroBrick I/O - Industrial Control Links

MicroBrick Distributed I/O Modulesin transient protection, a suppression diode is not typically required across relay coilsor other inductive loads.The FET outputs are designed to operate in 12 and 24 volt control systems, withcontrol voltages of up to 28 volts DC. An external power source is NOT required topower the MicroBrick FET output circuitry, but IS required by the load devices. FEToutputs ARE sensitive to signal polarity, driving DC control devices with a open drainoutput that switches to a common “ground”. When turned ON, the outputs have a verylow (< 2Ω ) resistance to the common. When turned OFF, the outputs exhibit very highresistance and low leakage that will not provide a false ON to sensitive controllerinputs like other solid state outputs have in the past. If an output drives a lowresistance or shorted load, it will be protected automatically by switching to a lowcurrent, high resistance state. The output will continue to sink some current in thiscondition until the overload is removed. Once the fault condition is cleared, the outputwill automatically switch back to its normal low resistance, driving the full currentrequired by the load.LED Output Status IndicatorsEach discrete output has an LED indicator to show the current ON or OFF state of theoutput. Typically, the state of the LED indicator mimics the state of the outputcommanded by a Host, unless the output is “forced” on or off. When the state of anoutput is forced, the LED shows the forced state that is actually driving the fielddevice, not what the Host is calling for.I/O Processor FunctionsMicroBrick Combo modules are sometimes used to flash alarm indicators remotely,but without help from the on-board microprocessor, variations in communications andI/O scan time can make the flashing look erratic. Each of the MicroBrick ComboModule discrete outputs has a precise flashing capability that is independent ofcommunications I/O speed or scan time. Two control bits are used per output; one toturn the output ON or OFF, the second to command the output to flash whenever it isturned ON by the first bit. A separate Modbus holding register sets the flashing rate.Combo Module Analog Input SectionMicroBrick Combo module Analog Inputs accept signals from sensors that monitorlevels, flows, temperatures, pressures, etc. Measurements are made with a highaccuracy16-bit Analog-to-Digital (A/D) converter. The Combo modules have a total of6 analog inputs.Signal Types and LevelsMicroBrick Combo Module analog inputs may be individually configured to acceptstandard 5V or 20mA process control signals. For each analog channel, the userconfigures the I/O module for the correct input mode (voltage or current). Theconfiguration information is nonvolatile and need only be set once unless the systemis changed. The Module uses the configuration information to determine whichcalibration tables to use for processing analog input conversion and calibration datafor each channel. The user must also set switches on the side of the Module thatenable precision current sense resistors required for 20mA operation but are not usedfor 5Vdc operation.Copyright © 2007 Industrial Control Links, Inc. All Right Reserved73