DL405 PID Loop issue

Hi all,

Hopefully somebody has a quick and easy answer to this one. I had to make some program modicfications to an existing program in a DL405 (450CPU). I made the changes, all went well and I wrote the program to the PLC to update the changes. However, now I do not seem to be getting any output from all three of the PID loops. I checked them, and all programming in terms of V locations, etc is still there. Did I stop the loops somehow when I made the proramming changes? I checked the output V memory locations in a data view table and they are zero for all 3 loop outputs??? Also, the Process Variables are loaded into the appropriate V-memory locationsas well. Is this a Directlogic glitch?? Thanks in advance for any help.

Sincerely,

SG

Bit 1 in Word 6 is the Automatic Mode Indication this bit should be on. If it isn't try turning Bit 1 in Word 1 on, this should turn it back into Automatic Mode.

Word 1 = Address + 0
Word 6 = Address + 5

Or in DirectSoft go View >> PID View and check that the Mode is in Auto for all loops.

You could try checking the firmware version in the PLC in case it needs to be flashed to your current software version.

How do I check the firmware, and then how would I flash it if it does not match my current software version (V4.0 build 20)?

Thanks,

SG

Go to the automation direct web site
http://support.automationdirect.com/downloads.html
They have installation utilities and .bin files.

It all depends on how you went about downloading the program to the PLC.

Basically in Directsoft there are two program download methods, Write Program and Save Project.

Write Program - Saves only the ladder portion of the program. Does not write any Vmemory or other variables to the disk or PLC.

Save Project - Saves almost everything including Vmemory, most set up values, and the ladder to the disk or PLC.

So if you did a Save Project and the PID variables had not been saved with a previous Save Project, then you would naturally enough get zero in those memory locations.

And it is possible that the loops went out of auto mode when you downloaded the program. It might also be due to your retentive ranges for your variables. If a variable that might stop the loop changed during the time it takes to download or if you did a Save Project, the loop could have dropped to manual.

Well, turns out the loops were in manual mode, so I went to PID view and changed them back to Auto; this is good info for future programming in directsoft; Thanks for the great tips!

SG