Purchase now: Allen Bradley 1746-NIO4I Analog Combo Module
Purchase now: Atlantechdrives provides you the 1746-NIO4I, a highly specialized combination analog I/O module manufactured by Allen Bradley for the SLC 500 control platform. This hybrid module provides 2 analog input channels (configurable for voltage or current) and 2 analog output channels that are strictly dedicated to generating Current (mA) signals (indicated by the «I» in the part number). This 2-in / 2-out configuration is incredibly efficient for «Closed-Loop» or PID control scenarios. For example, you can use one input to read the pressure from a pipe, and use one output to dynamically adjust the speed of a Variable Frequency Drive (VFD) controlling the pump, all processed through a single chassis slot.
Technical Specifications of the 1746-NIO4I
The 1746-NIO4I is engineered to provide precise control in demanding industrial environments. The inputs feature 16-bit resolution for highly accurate readings, while the current outputs utilize a 14-bit digital-to-analog converter to generate smooth, stepless control signals. The outputs are highly immune to electrical noise over long cable runs.
- Part Number: 1746-NIO4I
- Module Type: Combination Analog I/O
- Inputs: 2 Channels (Selectable: +/-10V, 0-10V, 4-20mA, 0-20mA)
- Outputs: 2 Channels (Current ONLY: 0-20mA, 4-20mA)
- Input Resolution: 16-bit
- Output Resolution: 14-bit
- Backplane Current Draw: 55 mA at 5V DC, 145 mA at 24V DC
- External Power Requirement: 24V DC required for outputs
Expert Tips: The Advantage of Current Outputs
Choosing between the NIO4I and the NIO4V is a critical engineering decision. Expert Tip: You should choose the 1746-NIO4I (Current output) whenever the device you are trying to control—such as a VFD or a proportional control valve—is located far away from the PLC cabinet. A 4-20mA current signal is highly immune to «voltage drop» and electromagnetic interference (EMI). Even if the cable is 300 feet long, 10mA sent by the PLC will be exactly 10mA when it reaches the drive. Just ensure that the total impedance of the receiving device and the wire does not exceed the module’s 500-ohm maximum load resistance limit, or the module will fail to push the current through the loop.
Maintenance and External Power
A common mistake when setting up the 1746-NIO4I is forgetting the external power connection. While the module communicates with the CPU via the 5V backplane, the internal amplifiers that generate the 4-20mA output signals require a robust, external 24V DC power supply wired directly to the front terminal block. If your PLC logic is commanding an output but the field device isn’t responding, check the external 24V DC supply first. Also, verify that your PLC program is scaling the data correctly (e.g., 0 to 32767 proportional counts matching 4 to 20mA).
Frequently Asked Questions (FAQs)
Q: Can I change the outputs of the 1746-NIO4I to 0-10V DC?
A: No. The output circuitry on the «I» version is hardware-locked to generate current (mA) only. If you need voltage outputs, you must purchase the 1746-NIO4V.
Q: How do I configure the two input channels?
A: Like standard SLC analog inputs, the 2 input channels use physical DIP switches on the module board to select whether they will receive a voltage or current signal from your sensors.
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This combo current module is an efficient choice for closed-loop control in an 1746-A7 chassis.
