How to install the Rockwell Automation 1756 series ControlNet communication module?

(2) Disassembly steps

Press the upper/lower tabs on both sides of the module to unlock it;

Smoothly slide the module out of the chassis, and power off in hazardous areas first.

3. ControlNet network wiring (Tap connection)

The module needs to be connected to the network through a ControlNet tap (Tap, such as 1786-TPR/TPS/TPYR/TPYS/TCT2BD1), with the following specific requirements:

Media type wiring method

Non redundant (CN2/CN2K) only connects the tap to module A channel (B channel is not used), and the tap needs to be selected as a direct connection type (such as 1786-TPS) to adapt to the BNC interface at the bottom of the module

Redundant (CN2R/CN2RK/CN2RXT) tap A is connected to module A channel, and tap B is connected to module B channel; Dual links need to be simultaneously connected to the network backbone (Trunk Line A/B)

Key wiring precautions:

Unused ports (such as the B channel of CN2) need to retain protective plugs (pre installed with the "K" model) to ensure the anti-corrosion level;

When the tap changer is disconnected from the module, it is necessary to immediately cover it with a dust cap to prevent the metal part from contacting the grounding surface;

In a redundant system, the main/backup modules need to be connected to the same network segment (such as the main module A channel connected to Trunk A, and the backup module A channel also needs to be connected to Trunk A).

4. USB port usage specifications

The module is equipped with a USB 2.0 Type B port, which is only used for temporary local programming. Core limitations:

Prohibited from use in hazardous areas;

Cable length ≤ 3 meters (9.84 feet), cannot be connected to a USB hub;

RSLinx Classic 2.55 and above software must be installed;

It is prohibited to upgrade multiple module firmware through USB at the same time to avoid upgrade failure.

Module reset and troubleshooting

1. Restore factory settings (reset operation)

When a module needs to clear configuration or fix exceptions, the following steps can be performed:

Disconnect the power supply of the chassis and remove the module;

Set the dip switch to "00" (invalid address, only used for reset);

Reinstall the module and connect the power supply;

After the module displays "Reset Complete Change Switch Settings", disconnect the power and remove the module;

Return the dip switch to the target address (01~99/98), reinstall and power on.

2. Core methods for troubleshooting

By using the OK status indicator light and network channel indicator light (A/B) of the module to locate the fault, the key status interpretation is as follows:

(1) OK status indicator light (core fault diagnosis)

Reason and solution for malfunction of indicator light status display information

Turn off power failure or internal failure: Check the power connection and module for tightness. If it is ineffective, replace the module

Reset Complete Change Switch Settings address to 00 (invalid): Reset valid address (01~99/98)

Frequent red FAIL power on test failure: replace module directly

Flashing red DUPLICATE NOTE DETECTED Network address conflict: Replace with unique address

Flashing red Image update Needed firmware needs to be updated: Use ControlFLASH software to upgrade Boot image

Evergreen/Blinking Green CPU=xx% (xx ≥ 80) CPU utilization is too high (over 80%): Check the number of network connections and optimize the control program

Blinking green NET ERR network wiring error or no other nodes: Check cables, terminators, and ensure that at least one other node is online

(2) Network channel indicator light (A/B channel status)

Interpretation of indicator light status channel (A/B) status

Evergreen is operating normally, and channel communication is functioning properly

Flashing green/extinguishing temporary error, module can self recover

Flashing red/off media malfunction (such as disconnection, looseness) or no other nodes: Check cables, terminators, and add online nodes

Constant red channel fault: power off reset module, if ineffective, contact Rockwell technical support

Key technical parameters

Parameter category 1756-CN2/CN2K 1756-CN2R/CN2RK 1756-CN2RXT

Backboard current 1.1A (5.1V DC) 1.3A (5.1V DC) 1.3A (5.1V DC)

Working temperature: 0~60 ℃ (32~140 ℉) 0~60 ℃ (32~140 ℉) -25~70 ℃ (-13~158 ℉)

Isolation voltage 30V DC (continuous), basic insulation between ControlNet/USB and backplane (500V AC withstand voltage for 60 seconds) on the same left (redundant models additionally support A/B channel isolation) on the same left

Anti corrosion grade (with "K") ASTM B845-97 G3 grade (ANSI/ISA 71.04), IEC 60721-3-3 CX grade same as left

The wiring category for ControlNet ports is Class 1, and for USB ports it is Class 3. Same as left