Accessing specific bits in a word.

[MamoJaLatam]

Hello,

I'm new to PLCs, now I learned about the "." operator, but it seems limited to specified registers only. So, for example, this works:

D100.1 := 1;

Question 1 - Is it possible to somehow access a specific bit of a label?  Something like:

myLabel.1 := 1;

Question 2 - Same, but this time with Z registers:

Z1 := 1;
myLabel.Z1 := 1;

Both examples throw a parser error. For now I'm sticking to assigning label value to a register, THEN changing the bit, THEN assigning the changed register back to my label, but it just looks ugly. Is there a better way to solve this? I'm using FX3G series.

[Inntele]

No.
If you want to check a specified bit of the word, you should move the word to the bit memory.
 

LD TRUE
MOV D200 K4M200
LD M204
OUT Y0

The index registers can not be used for this purpose too. It can be done by a complex way:
 

LD TRUE
MOV D200 K4M200
MOV K1M200Z K1M200
LD  M200
OUT Y0

Read the programming manual carefully. There is written all.

[collinsd70]

If you have access to predefined Mitsubishi Functions- you can also use the conversion to Bit Array- this is what I normally use, then specify your Tag[x] where x is the position of the bit you wish to analyse. 

Here is an example for a 16-Bit Integer

 

 

 

BitArray.bmp

[Inntele]

collinsd70, 

INT_TO_BITARR 16 = MOV Dxxxx K4Myyyyy. It's just an IEC interpretation of MELSEC command instruction.

[kaare_t]

You are correct that "." are limited to specific addressing only. The way "around" it is to define variables in global lists and then use the variable name (you can assign a labelname the address D100.1 for example).

[Gambit]

I think you want to use an Array.

Like than you can acces is like the following.

Arrayname[Z0] But you do  not have to use a direct indes register you can alos define a word Arrayname[index]

 

 

[mavbr42]

On 18/06/2018 at 10:40 AM, kaare_t said:

You are correct that "." are limited to specific addressing only. The way "around" it is to define variables in global lists and then use the variable name (you can assign a labelname the address D100.1 for example).

Thanks man, exactly the right answer that I was looking for !

Perfect :)

[Saxony Thermal]

Hello, quick question,

Using the syntax D100.1 as shown above works up to D100.9, but in GXworks3 D100.10 is a syntax error.
These are 16 bit devices, how do we access the remaining bits like this?

[Saxony Thermal]

Figured it out. D100.a is the tenth bit.

So...
D100.A
D100.B

D100.C
D100.D

D100.E
D100.F

It's in hex for selecting which bit to access, but the device number is decimal. Kinda funny but makes sense.