Forcing outputs on a DL-305?

ajbachhuber

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Join Date
Aug 2003
Location
New Hampshire
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Is it possible to force an output on or off with a DL-305. My assumption is that these are older units and that wasn't an option?

I've got mostly 05, 105 and 205s. I know the 305 is a little different and I've only got two here in the plant so my experience is minimal. I was trying to figure out what an unmarked I/O point went to without tracing the wires around throughout the enclosure. The dope who was here before me was the most cryptic programmer. He thought that it would mean job security and guess who's not here. Oh yeah and he didn't believe in wire troughs. "They create too much noise." We are dealing with 24vdc discrete signals here, no analog, no RF. Now it just means more headaches for me.

Anyway thanks for letting me complain about the misery that is my workplace. Any help I could get would be good. I was trying to use the Data View to look at the output and force it on. I suppose I could put in an "always on" contact and go from there but that is more screwing around than I wanted to do.

Thanks again.
-AJ-
 
I'm not sure if it's 'different' in the 305s (I haven't used them), but instead of using data view, it's a lot easier to use the 'change value' window. Click on the 'Y2=' icon, or CTRL+SHIFT+F2 key combination.

Rememeber that if the output is being turned OFF in the program, forcing it ON will only keep it ON until the program turns it OFF.

Regarding wiring troughs (or gutters)... I think AJ might be referring to what I would call wire duct... :confused:

This stuff:

narrowslot_wireduct.jpg


beerchug

-Eric
 
Yeah, wire duct...

I couldn't get duct out but trough came to mind. Thanks, Eric.

I tried the change value route too. It said "Cannot write a single bit." I guess that's the answer then.

POOP!! šŸ™ƒ
 
Ta for the reply Eric Firealarm and AJ
Yep ducting or duct is the term we use down here. A trough is something sheep drink out of on sheep stations, or what cowboys in US movies get knocked through the saloon doors into.
 
OK here's my 2 cents on the trough thing...trough is a viable term. It may not be what was meant in the post but it can apply to wiring.

What comes to mind when thinking of a trough?....A open pipe that carries water? An open container that holds water...remember the old western movies that had horse troughs?

Another term thats used is raceway. In my little bit of experience a trough may or may not be open. In many cases it is OPEN...ie no cover and carries large conductors to feed busbars etc

I have also seen items that were termed raceways or troughs...ie were 4" square or larger and the one side opened or was open to allow access to place wires etc.

Trough is a viable term in the electrical field to portray an item that is larger than conduit (at least as large as 4" conduit") but is open OR has an opening that allows access to place wires. Normally this item is square or rectangular.

Personally I dont hear the term "duct" much except relating to that plastic stuff used in control panels, the stuff that looks like the pic in Eric's post. I have used alot of that stuff too.
 
To add to the confusion...

I've heard all of the decribed items called by any and all of the aforementioned names. Here's a picture of what I think Ron is referring to...

corel006.jpg


Most of the emclosures manufacturers refer to these two types by the names used in the picture. IOW, a "trough" has closed ends, and is basically a long, skinny enclosure. A "wireway" has open ends which you connect to fittings and other wireways. Like this:
[attachment]
Notice how quickly we turned AJ's original question into something COMPLETELY DIFFERENT?... :D

beerchug

-Eric

wireway.jpg
 
For those who work with AD plc's here is the answer. This answer is specific to Directsoft.

DirectNET protocol (also known in the past as TIWAY) which is available in all AD plc's and is the only way to communicate with a D3-330, D3-340, or GE Series One, cannot do bit level editing. IE. you cannot "force" a single bit.

Bit level forcing also cannot be done on the D2-230 processor.
 
There is a workaround for forcing outputs in the 305. Insert an END or NOP at the beginning of the ladder program. This will disable the ladders from executing. You are correct about the bit level writes but you can write a byte at a time. Read the pattern up in data view, alter the bit you wish and write it back to the CPU. Easier to do if displaying the value as a bit pattern instead of a value. I/O can be accessed by the R data type. R0 = I/O 0-7, R1 = I/O 10-17, etc. The same method can be used on the DL230 CPU but the 230 can do bit level writes, it uses K sequence protocol.

The protocol AD calls Directnet, TI and Siemens called Hostlink and before that GE called it CCM2. Same protocol, different names.

Hope this helps.....
 
Back to-off the subject!

The term raceway is an NEC term and includes just about any kind of enclosed conduit/wiretray.

From NEC '02:

Raceway. An enclosed channel of metal or nonmetallic materials designed expressly for holding wires, cables, or busbars, with additional functions as permitted in this Code. Raceways include, but are not limited to, rigid metal conduit, rigid nonmetallic conduit, intermediate metal conduit, liquidtight flexible conduit, flexible metallic tubing, flexible metal conduit, electrical nonmetallic tubing, electrical metallic tubing, underfloor raceways, cellular concrete floor raceways, cellular metal floor raceways, surface raceways, wireways, and busways.
 
It is possible to force I/O with DirectSoft and at least most of the 305 models. (I'm not sure about the very oldest versions).

Don't do it from the Alt-Debug-Change Value. Go top the Debug menu and open a Data View (or a watch window in the oldest DirectSoft versions.)

Go to options, and under set it up for read/write and enable the overrides.

Connect to the PLC, and in the far right hand column of the data view window you will have two sets of two buttons you can click. One sets the off/on status and the other turns the override logic enable on or off. Enter Y0 (for example) Click the override on, click the ON status, and up at the top click the "to PLC" icon for a single point. That should force the I/O on.

Two other points. First, AutomationDirect has two protocols, and I believe they are BOTH available in all models. The "programming" protocol is K-Sequence, and if you connect to the PLC using it you CAN change a single bit from the Alt-Debug-ChangeValue box. The second protocol is DirectNet. It will only transmit a word at a time. If you want to change a single bit, change the display format from Bit to Word and binary. You can change the single bit you are interested (second from the right for Y1, for example) and sent the whole word back. It may not help, though, because unlikethe override method above the internal logic will re-write the status next scan.

Second point, unless the I/O is only controlling simple things like lights, forcing I/O can be a very dangerous way to trace wiring, since SOMETHING may come on in a location or sequence that will (by Murphy's Law) produce undesired results!
 
Thanks guys

Andy,
I was not aware of the use of the R data type. That's good to know. That is what I'll do.

Icky,
I didn't know that the 230 didn't allow bit forces either.

Tom,
You and Andy were right on the ball. As far as the scan resetting the bit, Andy has a solution for that too. This isn't a particularly dangerous application, it's only a table top machine so I can see the whole thing at once and the outputs only control pneumatic solenoids. I checked the clearance of all the components with the manual overrides before I tried to force the bits. The control and override buttons in the Data View were what I was looking for too. Apparently you don't get that with the 330, 340 and the 230. Who knew? :confused:

I found the problem by chasing wires and ohming cables. It was an undocumented change. Typical :rolleyes:

So was the consensus that DirectNet won't allow bit level forces? When settting up a link the software prompts for the protocol to use, so as long as it isn't a D3-330, D3-340 or a D2-230 then I should choose K-sequence? Or is there more to it?

Thanks
-AJ-
 
K sequence is your only option with the DL230 CPU AJ. And once again the 230 will allow you to write to a single bit but does not support the "Bit Override" some of the other CPUs do. If the situation allows, use the END statement.
 
If you want to turn the output on and keep it on, just to see what actions takes place, why don't you hard wire from the output terminal to the common?
 

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