Odesta has experience with multiple PLC-5 migrations and is able to help you through that transition. There are several options to consider:
Phased migration - This would be the typical approach that most manufacturers take, due to the limited amount of downtime that is available. Depending on the number of Remote I/O and the HMIs involved this could range from a few hours to 1 to 2 days. This would allow you to continue to use your existing legacy Remote I/O devices, including the original main PLC rack, by adding an ASB to the main rack. The main rack would need to be evaluated to see if the required response time of the original I/O modules can be allowed to migrate to Remote I/O (RIO). The critical response time modules will need to be migrated to the new ControlLogix rack if they require a fast response. The modules that usually need to be migrated at the beginning include fast analog, resolver, high speed counters, etc.
This type of migration is fairly quick and maintains the same program structure and the I/O tags will be named similar to the PLC-5 I/O to ease the transition.
Complete upgrade - This would require a complete replacement of the 1771 I/O with the equivalent ControlLogix modules, racks and new remote I/O network choice (ControlNet, EtherNet/IP or DeviceNet). With this option it may also be desirable to evaluate how much of the logic should be completely re-written to take full advantage of the capabilities of the newer ControlLogix platform (User Defined Data Types, Add-On Instructions, Phase Manager, etc.)
Odesta is able to provide support and engineering for the equipment evaluation, electrical schematic updates, electrical installation, HMI updates/modifications and the PLC programming.
Contact us to help you increase your equipment value and capabilities with an upgrade to the ControlLogix platform.