We are preparing to install a used fabric processing line including seven large DC drive systems. It has a Modicon 984 PLC, three PanelMates, and the seven Siemens drives on a Modbus network. The PLC will be replaced with, you guessed it, ControlLogix. The debate is currently, should we abandon modbus in favor of harwired control? I have the docs for the drives and they are loaded with features. Our plant uses A/B, and Reliance products. We are comfortable with RIO, DH+, and are learning ControlNet. If we keep Modbus, which none of us have ever worked with, we don't have to fool with the panelmate comm. changeover, and may get a lot of valuable information to and from the drives, once we pass the learning curve. If we switch to harwired control, we know we can commision a functional machine, but will have to change the PanelMates comm. (easy, but expensive), add two analog output cards, (also expensive) and end up with very little feedback from the drives. Can CLogix do Modbus? Where can I get manuals for the modbus interface on these old Siemens Simoreg DC Drives? I've been to their website and found hardware and setup manuals, but nothing on the comm. cards. Oh by the way, our controls upgrade budget is about $20k! It barely covers hardware costs... That means we get to do all the engineering in house with our own talents and no hired help! I love my Job.