What instruction is a one shot for direct logic 405 software

darrentpi · Jun 5, 2005

Just curious what is considered a one shot with direct logic software.
Help would be great thanks
DM

rsdoran · Jun 5, 2005

The Positive Differential instruction is typically known as a one shot. When the input logic produces an off to on transition, the output will energize for one CPU scan. PD is a coil instruction.
-(PD)-

Tark · Jun 6, 2005

You can use a positive differential as a contact. There is a negative differential contact as well.

rsdoran · Jun 6, 2005

Tark said:
You can use a positive differential as a contact. There is a negative differential contact as well.

Lets clarify this. I have always used the coil instruction then used a contact for that coil instruction, old habits die hard.

There are other contact instructions that may be used too.
STRPD
STRND
ANDPD
ANDND
ORPD
ORND

Tark · Jun 6, 2005

rsdoran said:
There are other contact instructions that may be used too.
STRPD
STRND
ANDPD
ANDND
ORPD
ORND

Yes these are listed as different instructions, but depending on how you look at it they are all just the same PD and ND instructions. The difference is how they are used in a rung, which doesn't matter to the programmer if you are using Directsoft, but it does matter if you are using a keypad programmer.

I use the contacts, I find them easier to read. Although if your "old" you might find the coil easier.

elevmike · Jun 6, 2005

Depending on the processor, he may be able to use a PD contact that would operate from an normal coil. A word to the wise though, if your using a mechanical switch you might get a bounce, causing the PD to double "click".

In directsoft Edit mode, hit F7 then click on the contact tab, then click on Differential.

Edit: the PD contact is only avialable on the 450 cpu. All others will need a PD coil, then use a contact from that coil.

testsubject · Jun 6, 2005

elevmike said:
Depending on the processor, he may be able to use a PD contact that would operate from an normal coil. A word to the wise though, if your using a mechanical switch you might get a bounce, causing the PD to double "click".

In directsoft Edit mode, hit F7 then click on the contact tab, then click on Differential.

Edit: the PD contact is only avialable on the 450 cpu. All others will need a PD coil, then use a contact from that coil.

Mike,

That is not true. I use the PD contact with the 250-1, the 260, and the 06. You may be looking in one of the older books.

Bob

elevmike · Jun 6, 2005

Bob, I know, but the thread is about the 405 series CPUs..(I think)

testsubject · Jun 6, 2005

Mike,

I understand your response now. That being said, I do not know if the other 405 series CPUs use the PD contact.

Bob

What instruction is a one shot for direct logic 405 software

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