Manufacturer Rockwell Automation
Brand Allen Bradley
Part Number/Catalogue Number 1756- MYR 2
Series ControlLogix
Module Type Enhanced redundant module
The Allen-Bradley 1756-RM2 is a ControlLogix redundant module. It has enhanced features for speeds up to 1000 Mbps. When paired with the 1756-L7x controller in both cases, it provides the best scanning performance. For cross-loading, the 1756-RM2 uses redundant fiber ports with no single point of failure. During channel switching, the processing chassis stays synchronized, while scan times can experience a delay of about 10 milliseconds. It features enhanced security features and interference-free diagnostics.
The 1756-RM2 redundant module consumes 1.16A current at 5.1V DC and 3.4 mA current at 24V DC. It has a maximum power consumption of 6W and a thermal dissipation of 21 BTU/hr. It can be installed in any slot in the ControlLogix chassis. 1756-RM2 weighs 0.64 LBS and has an open shell. In terms of communication, it supports up to seven enhanced ControlNet and EtherNet/IP communication modules. In terms of cabling, the 1756-RM2 supports 1756-RMC1, 1756-RMC3 and 1756-RMC10 cables with lengths of 1m, 3m and 10m respectively.
The ControlLogix 5560 and ControlLogix 5570 series controllers support 1756-RM2 modules. Redundant module configuration tool RSLinx 2.59.
Depending on the combination of redundant modules used, various synchronization speeds can be enabled. In particular, if used with the same 1756-RM2 module, speeds can be as high as 1000 Mbps. If you use A series or B Series 1756-RM2 at the same time, the speed can be as high as 100 Mbps. Controller switching up to 20 ms is possible with the 1756-RM2 redundant module.
Unlike the first version of the redundant module, the 1756-RM2 occupies only a single slot in any ControlLogix chassis. To implement redundancy, a pair of redundant racks must be installed. Each rack houses the same controller type and version. I/O modules, smart modules, and encompass Partner modules cannot be installed in any redundant chassis pair. These modules must be installed on a chassis of level 3 or higher, depending on the number of nodes supported by the communication module used.
The redundant module has an integrated fiber optic connector where controller synchronization is taking place. The cable has LC connectors and is 8.5/125 micron single-mode cable. A maximum distance of 10 km (10,000 m, 10,936.13 yd) can be established between each redundant module, however, the ideal situation is for the redundant chassis to be close to each other.
