Gator

RSWho, which is a seperate application that "remembers" any and all past connections, runs inside of RSLinx. A red X through a connection indicates that RSLinx RSWho cannot find it. If you right click on the offending connection, and select "remove", you can send it permanently to the ozone. At your service: The PLCProfesser

My apologies, I did not read all of the posts in this thread. But, the PIC driver has a check box that is usually checked to get the device to work with the lengthy handshaking with W2000 and up. If you delete this driver without first unchecking that box, you have temporarily shot your foof off because you cannot get back in to release the comm port. If this is the case, right click on "My Computer" >> Device Manager >> Open serial ports and delete the port. Reboot and the comm port should reload and you are back in business. PIC modules are the kiss of death, but if that is all you have, use it with caution. Tim Gates PLC Professor

My apologies, I did not read your post in depth, but I will comment on counting down with timers. You can use a counter data type and execute the instructions with the CTD control bit or you can use the SUB instruction. 1. Use a TON with a preset of 1 second and place a "true if off" instruction in the rung that addresses the .DN bit for that timer data type "T4:0.DN". This will allow the timer to energize the DONE bit for one program scan every second. 2. Use this .DN bit to execute a CTD of the counter data type "C5:0". OR, use the .DN bit to SUB subtract one from your count. Because the .DN bit is only true for one scan, it is not neccesary to one shot this rung. I would send you a program file with this logic, but I do not have a current version of 500 that includes the new 1400 processor. If you need more help, I could send a file for an 1100. Most of my projects are RSLogix5000 these days. Tim Gates PLC Professor

You have already received the answer that you were looking for, however, I would like to add that these are not really addresses, but they are predeclared variables or tagnames or pointers that point to the acutal memory locations used in the controller. All AB PLC's, excluding Automation Controllers control and compact logix, predefine all of the variables for you. Although it is conventional to refer to these as addresses, it is good to keep in mind that they are pointers and move around in actual memory locations depending upon the expansion and contraction of your data files. The convention of I:0.0/00, O:0.0/00, B3:0/0 etc only exist on your laptop and not in the controller. It is not neccesary to know this to write code for a PLC, but it is nice to know.

I was thinking of a home study course that I could purchase and use with a Micrologix1000 10pt. processor and the free software from Rockwell. The demo is very easy and inexpensive to assemble with a processor and $35.00 worth of Radio Shack parts. Any other ideas on where to get project lab books and lessons on PLC's? Thanks: Tim

What does anyone reccommend for a training package aimed at learning how PLC's "think" as well as how to program them. Using a real, but inexpensive PLC demo unit. And has lab projects for the more advanced instructions as well as the basic instructions? Simulators are great and inexpensive but lack the hands on experience that you feel when you have a real piece of hardware sitting right in front of you with the lights blinking.

Has anyone used the training package at the PLC Professor website? It is based on the free RSLogix500 software and the least expensive AB Micrologix1000.