Brand new to PLCs and RSLogix

Hi. I’m a retired SW engineer trying to modify a Microlinx 1200 program. I’m using RSLogix 500 starter. I’m brand new to PLCs and the Rockwell tools and have a few beginner questions. (I would experiment but I currently have no access to the PLC, and when I do, it will be very limited.)

1) When I download the program, is it stored in flash? i.e. will it survive when I unplug the cable? Will it survive a power failure on the PLC?

2) I know I have to configure the driver using RSlinx. After doing this, Do I need to manually run RSlinx before downloading, or is it automatically started and called when I select “download” in RSLogix?

3) I’m confused about examining data files while the PLC is running. Does RSLogix stop the scan to read the data files? If it does, then does it then automatically resume the scanning?

Thanks
Kip

1) When I download the program, is it stored in flash? i.e. will it survive when I unplug the cable? Will it survive a power failure on the PLC?

Click to expand...

Yes, it will hold the program. You can also install a memory module just in case.

2) I know I have to configure the driver using RSlinx. After doing this, Do I need to manually run RSlinx before downloading, or is it automatically started and called when I select “download” in RSLogix?

Click to expand...

RSLinx will start automatically, but I always like to start it manually just to make sure communications are working properly. My personnel preference.

3) I’m confused about examining data files while the PLC is running. Does RSLogix stop the scan to read the data files? If it does, then does it then automatically resume the scanning?

Click to expand...

Monitoring the program online will not stop it from running. It will continue to scan.

Mickey,
Thanks for the answers.
What is the value added of the memory module if the PLC already "holds" the program? Is it just more memory, or does it have some additional funcionality over the built-in memory?

Think of the Memory Module's role as similar to a recovery partition on a computer hard drive.

It's possible, though infrequent, for the nonvolatile RAM memory of a controller to be scrambled by electrical noise or spikes. In such a circumstance, the controller firmware can still reboot and look to the more-durable Memory Module for a copy of the program.

The Memory Modules also make it very easy to re-program an out-of-the-box controller, or to duplicate controller programs on multiple machines quickly and without using RSLogix software.

The Memory Modules don't expand the usable RAM of the controller; they are strictly a durable onboard storage device to hold a backup copy of the user program.

I understand. Thanks

1) When I download the program, is it stored in flash? i.e. will it survive when I unplug the cable? Will it survive a power failure on the PLC?

Click to expand...

The program in AB PLC's is stored in RAM memory, and normally has a battery to hold the program during power outages. For some processors, you may also install an EEProm, to load the memory from if the program is corrupt. (You must download to the memory module separate from the normal download). If the PLC is on, you may want to do an upload before powering it down the first time, just to make sure you have a copy.

2) I know I have to configure the driver using RSlinx. After doing this, Do I need to manually run RSlinx before downloading, or is it automatically started and called when I select “download” in RSLogix?

Click to expand...

If RSLinx is not started previously, you may get a timeout error the first time you try to communicate with the PLC. Normally attempting the action again (download,upload, or Go Online) will work the send time. You can also have RSLinx start with windows, however if you are using the DF1 driver, your serial port will not work, while RSlinx is open.

3) I’m confused about examining data files while the PLC is running. Does RSLogix stop the scan to read the data files? If it does, then does it then automatically resume the scanning?

Click to expand...

You can view while online and also upload, without effecting operations. If you download, from an offline file, or place the PLC in program mode, the ladder will cease to be scanned, and outputs will be disabled (off)