Allen-Bradley SLC 500 ™ 1746 series I/O modules

1746-NO4V 4-channel voltage (0-10V/± 10V) with the same structure as NO4I, output type is voltage, suitable for voltage control equipment, analog speed control motor, indicator light brightness adjustment

1746-NO8V 8-channel voltage (0-10V) 8-channel high-density, total output load current ≤ 100mA, supports synchronous control of multiple devices and multi-channel analog signal output (as displayed on the dashboard)

System installation and configuration

（1） Rack and power installation

Rack selection: Choose slot positions based on the number of modules. 1746-A7 (7 slots) is suitable for small and medium-sized systems, while 1746-A10 (10 slots) is suitable for large systems; If expansion is required, multiple rack connections can be achieved through the 1747-SN module.

Power calculation: It is necessary to calculate the 5V DC and 24V DC power consumption of all modules to ensure sufficient output capacity of the power module (e.g. 1746-P2 provides 24V DC 2.0A, 1746-P4 provides 4.0A). The calculation formula is: total power consumption=∑ (5V current of each module)+∑ (24V current of each module).

Installation specifications:

The rack should be installed vertically to avoid tilting (tilt angle ≤ 5 °) and ensure good heat dissipation;

The power module should be located near the input end of the rack to reduce wire voltage drop;

The grounding resistance is ≤ 4 Ω, and the rack shell needs to be separately grounded to avoid electromagnetic interference.

（2） Module installation steps

Static protection: Wear a grounding wristband before operation, store the module in an anti-static bag, and avoid touching the back panel pins.

Power off operation: Disconnect the power supply of the power rack before installation to prevent damage to the module or backplane caused by live plugging and unplugging.

Module insertion: Align the rack slot and slowly insert the module into the upper and lower self-locking tabs to secure it, without the need for additional screws; Idle slots require installation of 1746-N2 filling plates to prevent dust from entering.

Slot selection:

The processor module (such as 1747-L511) must be installed in slot 0;

Under high temperature conditions, install the heating module (such as a 32 point I/O module) in the rightmost slot (with a temperature tolerance of 60 ℃);

The analog module needs to be kept away from strong interference sources such as frequency converters and high-power motors to reduce signal fluctuations.

（3） Module address configuration

Address allocation principle:

Digital quantity module: Each 16 channel module occupies 1 input word/output word, and the 32 channel module occupies 2 input words/output words;

Analog module: Class 1 interface module (such as 1746-NI8) occupies 8 input words and 8 output words, while Class 3 interface module adds an additional status word address;

Address range: Input image area I: 0/0-I: 255/15, output image area O: 0/0-O: 255/15, avoid address overlap.

Configuration tool: Set the module ID code (such as 1746-NI8 Class 1 ID 3526) through RSLogix 500 programming software, and assign the corresponding input/output image area address. After configuration is complete, download it to the processor.

Wiring specifications and examples

（1） General Wiring Guidelines

Wire selection:

Digital module: Recommended 22-16 AWG shielded twisted pair (such as Belden 8761) to reduce electromagnetic interference;

Analog module: requires the use of twisted pair shielded wires (such as Belden 9239), with the shielding layer grounded at one end (near the signal source end) to avoid common mode interference;

Power cord: A 24V DC power supply requires the use of 18-14 AWG wires to ensure a voltage drop of ≤ 0.5V (the wire diameter needs to be increased for long-distance wiring).

Isolation and grounding:

The group isolation module needs to ensure that the common terminals (COM) of different groups are not connected together to avoid cross group short circuits;

The grounding of the analog module needs to be independent and separate from the power grounding, with a grounding resistance of ≤ 1 Ω;

The rack shell needs to be connected to the system grounding grid through grounding terminals to prevent static electricity accumulation.

Polarity and short circuit protection:

The DC module needs to strictly distinguish between positive and negative poles, and reverse connection may burn out the module (some modules have reverse connection protection);

The load end of the output module needs to be connected in series with a suitable fuse (such as 0.5A/250V) to prevent short circuit damage to the module caused by the load.

（2） Typical module wiring example

1746-IB32 (32 channel digital input):

4 sets of common terminals (COM1-COM4) correspond to channels 0-7, 8-15, 16-23, 24-31 respectively;

COM1-COM4 is connected to the negative pole of 24V DC, channels 0-31 are connected to the sensor output terminal, and+V1-V4 is connected to the positive pole of 24V DC;

When the current of a single group exceeds 2A, both common terminals of the group need to be connected simultaneously to avoid terminal overload.

1746-OB32E (32 channel digital output):

Two sets of common terminals (+V1,+V2) correspond to channels 0-15, 16-31;