Mitsubishi GX Works2

[Progammer]

Hello Everyone,

I am trying to learn the new mitsubishi software GX Works 2. I tried reading their manual but they dont explain really well the definition of variables.

I know siemens real well.

For example in siemens MD could be a double word or float.
or I is an input

please help and if possible do a compare with siemens variables so I can get a better clarifications.

Thanks

 

[dploof23]

Hello,

Attached is a screenshot from the GX Works2 programming manual. Also I can email you a copy of the manual of you don't have it. I tried to upload it here, but it is too big even if I compress it. PM me if you are interested.

Regards,
Dave

 

[Progammer]

Thanks

I have this already.

what is a step relay?
link relay?
edge relay?
latch relay?

i never encounter such relays in siemens plcs.

The only one that looks familiar is the internal relay which is an M bit.

I know in siemens to latch a bit you will use the set (s) command.

Is it different with mitsubishi you can not use an internal relay (M) to latch a bit?

thanks

 

[dploof23]

Thanks

I have this already.

what is a step relay?
link relay?
edge relay?
latch relay?

i never encounter such relays in siemens plcs.

The only one that looks familiar is the internal relay which is an M bit.

I know in siemens to latch a bit you will use the set (s) command.

Is it different with mitsubishi you can not use an internal relay (M) to latch a bit?

thanks

I have never used a step, edge, or link relay so without looking it up in the manual I couldn't tell you what they are specifically. I can say I have done extensive programming with Mitsubishi PLC's and never used those types of relays so I don't think you will need to worry about them right away.

To latch an 'M' bit it is simply entered as [SET M0], and to unlatch it would be [RST M0].

Hope this helps.

Dave

 

[adisharr]

From what I remember, the latch relays are battery backed in some models. Omron had something similar with the 'holding' relays. They would retain their state through a power cycle.

Link relays are used when networking between mutiple Mitsu PLC's. A portion of the link relay area is shared between PLC's so that changing a bit in one PLC will automaticaly update its state in all the others.

I image the step relays are used with some special instructions for sequential processing purposes.

 

[Progammer]

thank you all

can some one give me examples how each variable can be used. and may be the corresponding Siemens value.

 

[parky]

Latch relays or bits are the Data memory & M bits these can be set to retentive, in the project tree go to plc parameters and one of the last tabs are parameters there you can set the areas that retain data when plc in stop or powered down, on FX D200-255 are usually retentive by default but you can change this from D000 to Dxxx this applies to various other memory areas.
Link relays are used for comms, W words & B bits are very often used for network comms i.e. NetH these are configured in blocks as you require them for example plc1 could use W000 to W0f0 & B000 to B00ff other station would use W0100 to W01ff etc.
All user memory areas can be used just like M or D even if these are not used by comms it depends if you use GX Developer or GX Works on how you set the variables in the symbols, GX Dev only needs the first word for float as it automatically takes the second, in Works a Real or float is 32 bits so takes up D20 + D21
Arrays are as many words as required for example array 0..3 of byte is 4 bytes that's 2 words Dx to DX+1 array 0..3 of word takes up 4 words Dx to Dx+3 when you address an array you either use just the symbol i.e. Temperature this takes the whole array where Temperature[0] takes the first word only
When you create a function block with parameters what the compiler does is pass the input or in/out data to temporary scratch memory (real memory like D or M that is reserved for the compiler then jumps past the program end instruction to the code of the FB processes the code then returns and passes the temps back to the in/out data e.g. if FB has 2 input parameters 2 output parameters and 2 in/out the in and in/out values are transferred to temps the FB logic is processed then the resulting in/outs and the outs are passed back
in 1 > Temp1 in
in2 > temp2 in
Out1> Temp3 Out
In/out 1 > Temp4 in/out
In/out 2 > Temp 5 In/out
process FB code
Temp3 Out > Out1
Temp4 > In/out 1
Temp5 > In/Out 2
so it passes in
passes in/out both ways
Passes out out only
Seems a bit confusing but to keep compatibility with standard ladder it needs to be this way, you must keep the source code in Works as uploading from plc to Works will only give you STL code and probably make it difficult to understand as some of it is not easily de-compiled back to ladder.

 

[Marti9t9]

I hate to jump onto someone else's thread with another question but this topic is so relevant to me and I'm under a little pressure on site here.

My issue is that I'm using M bits all over my program but their state is being lost on power cycle of CPU. I was able to set what D registers I wanted to be retentive but the area to do the same is grey out for memory bits.

Should I have been using L bits since the start? I hope not. See image to help explain my problem

 

[jparale]

Auxiliary relay (M) has many devices application, depending on the relay number assignment. it also depends on the PLC type you are using.

Example: For FX2N
Gen. aux relay is M0 to M499
Battery backed/latch relay is from M500 to M3071

There were also a lot of auxiliary relay for special types of application that you can use. It is all listed in a Mitsubishi programming manual.

 

[jparale]

By the way I have been using a melsoft GX developer, I never had used GX works before but I presume it may not be the same but it will be similar in many application...

 

[Marti9t9]

Well I bit the bullet (no pun intended) and replaced all my M registers with L ones. Used the batch edit function in GX Works2 to replace 900 addresses. Thank God for excel.

 

[Ronnie Sullivan]

The S relays actually act differently from FX models to Q models.
In FX they are used for sequencing where only 1 step is active (or scanned)
The sequence is started by the instruction [STL] and is ended by [FEND]

Those instructions are not available in the Q so they are used to indicate a sequence or step.