Allen Bradley 1771-NB4T

The Allen Bradley 1771-NB4T is a PROFIBUS-DP communication module from the Rockwell 1771 series. You can think of it as a "translator" or a "bridge". In many factories, the equipment may come from different "countries" (brands), such as PLCs are from Rockwell (speaking "English"), but the frequency converters, sensors or instruments are from Siemens or other European brands (speaking "German"). They don't understand each other's language and can't communicate directly. The task of it is to enable Rockwell's PLC-5 or SLC 5/03 and above series PLCs to understand and command those devices that speak PROFIBUS "German", so that the entire automation system can work smoothly and collaboratively. Therefore, when your factory needs to buy this crucial "translator", choosing a reliable supplier is of utmost importance. We promise to provide original and brand-new modules to ensure that your old system can operate stably and for a long time.

Efficiency improvement

1. Previously, connecting a device might require pulling more than a dozen wires. Now, only one bus cable and a few connectors are needed, significantly reducing the installation time.

2. Through the configuration software, engineers can view the entire network status on the computer and quickly locate communication issues, instead of using a multimeter to check one wire at a time as they did before.

3. When a device malfunctions, the diagnostic information of the module can quickly tell you which slave station has disconnected, and the maintenance personnel can directly go to check that device, rather than searching everywhere for the problem, greatly shortening the downtime.

4. Large amounts of data can be read from the device at once (such as the operating current, frequency, fault codes of the frequency converter, etc.), instead of being able to read only a simple signal as before. The information is more comprehensive and the control is more precise.

Core interest point

1. The greatest advantage is that different brand devices can coexist harmoniously within one system. You don't have to replace all the Siemens frequency converters just to use Rockwell's PLC, saving a significant amount of money.

2. Compared to the traditional point-to-point hard wiring, PROFIBUS allows many devices to be connected on a single bus cable. The more devices there are, the more noticeable the cost savings in terms of cables, racks, and construction, and the cleaner the cabinet will be.

3. Digital communication is more precise, has stronger anti-interference capabilities, and data transmission is faster, enabling the entire control system to achieve a higher level of response speed and stability.

4. For those PLC-5 systems that are still operating stably, if new PROFIBUS devices need to be added, this module is the best choice, avoiding the huge investment in upgrading the entire system.

Compatibility and Integration

1.The Allen Bradley 1771-NB4T is mainly designed for use in conjunction with PLC-5 and SLC 5/03 and above series processors. Note that it cannot be used on more modern ControlLogix or CompactLogix platforms, which have corresponding 1756 or 1769 series modules.

2. It must be installed in the 1771 series I/O rack, such as 1771-A1B, 1771-A2B, 1771-A3B, etc.

3. As the master station, it can integrate most third-party devices that support the PROFIBUS-DP slave protocol, such as frequency converters, starters, instruments, I/O modules, etc. from brands like Siemens, SEW, and Danfoss. The compatibility is very extensive, and it is truly a "jack of all trades".

4. RSLogix 5 or RSLogix 500 must be used to write PLC programs, and data can be exchanged with 1771-NB4T through block transfer instructions (BTR/BTW). At the same time, RSNetWorx for PROFIBUS software must be used to configure the entire PROFIBUS network.

FAQ

Q1: Can this module be used on my ControlLogix rack?

A: The Allen Bradley 1771-NB4T is a module of the 1771 architecture and can only be used in PLC-5 and SLC 500 systems. The ControlLogix system requires the use of 1756-DNB or 1756-DNBH modules.

Q2: How can I know if my PLC program is correctly reading and writing data?

A: In the PLC program, you need to use the block transfer read (BTR) and block transfer write (BTW) instructions to communicate with the module. You can monitor the "completion bit" (DN) and "error bit" (ER) of these instructions, as well as the data in the data table, to determine if the communication is normal.

Q3: Can the equipment I have, which is PROFIBUS-PA, be directly connected?

A: No, it cannot. PROFIBUS-PA is a safe bus used for process automation. You need a DP/PA coupler or link to connect the PA segment to the DP network, and then the Allen Bradley 1771-NB4T can communicate with the PA device.