How do we decide in programming a PLC that we use comparator, timer, registers, flags

How do we decide in programming a PLC that we use comparator, timer, registers, flags, function blocks etc for any task or for any network ?

thanks in advance

first what you have to do decide
and second when there is any compression use compare,any time delay use timer TON,tof,rto based on application
do one thing go to the basic programming of plc pick some easy task and made it...
what is your plc and what is your application or only you want to learn plc.....specify then ask....

can you give me the simplest of examples of how to selecting these things in our requ

md.abdullah said:

first what you have to do decide
and second when there is any compression use compare,any time delay use timer TON,tof,rto based on application
do one thing go to the basic programming of plc pick some easy task and made it...
what is your plc and what is your application or only you want to learn plc.....specify then ask....

Click to expand...

just want to learn ...........

can you give me the simplest of examples of how to selecting these things in our required program ?

for comparators, timers, function blocks, registers , flags etc ........

dear read this one...
http://www.plcs.net/contents.shtml
and tell me what type of plc do you want to work...or learn
i may be recommend you try Allen bradly first its very easy.....go to the AB website or some local vender they will provide you software then try this on that...you cant learn plc on air first you must have some software then the basic of plc and apply this one to you software in simulation way...
best of luck....

md.abdullah said:

dear read this one...
http://www.plcs.net/contents.shtml
and tell me what type of plc do you want to work...or learn
i may be recommend you try Allen bradly first its very easy.....go to the AB website or some local vender they will provide you software then try this on that...you cant learn plc on air first you must have some software then the basic of plc and apply this one to you software in simulation way...
best of luck....

Click to expand...

I want to learn Siemens S7 200 & 300 ......... what should i do ? what software should i need ? How to learn ladder logic programming ?

thanks for your replies

for the s7-200 microwin v4
and s7-300 simatic manager software are used
first collect some basic document about 200 and software and get the software from siemens website install and play...with simulation enviroment...software also has simulator...

if you want to learn siemens s7-200,you must have the STEP7/MicroWIN software,add to learn s7-300 or s7-400 must use the STEP7 software.

phatcreators said:

How do we decide in programming a PLC that we use (1)comparator, (2)timer, (3)registers, (4)flags, (5)function blocks etc for any task or for any network ?

thanks in advance

Click to expand...

Use (1)compare instructions when you want to compare numerical data stored in (3)registers. The result of the comparison instructions is usually stored in single-bit (3)registers, called (4)flags. Compare instructions are instructions like (I have used the A-B mnemonics, the Siemens may be similar) ...

EQU equal
NEQ not equal
GRT greater than
LES less than
GEQ greater than or equal
LEQ less than or equal

Use (2)timer instructions to a) time an event, b) generate a time period (eg. a delay), c) generate a cyclic clock pulse, d) accumulate run hours for a piece of equipment.

Use (5)function blocks for other logic, eg PID control, program looping etc. There are many different (5)function blocks for a wide range of functions...

How to download the program inside Simatic S7 Manager ?

daba said:

Use (1)compare instructions when you want to compare numerical data stored in (3)registers. The result of the comparison instructions is usually stored in single-bit (3)registers, called (4)flags. Compare instructions are instructions like (I have used the A-B mnemonics, the Siemens may be similar) ...

EQU equal
NEQ not equal
GRT greater than
LES less than
GEQ greater than or equal
LEQ less than or equal

Use (2)timer instructions to a) time an event, b) generate a time period (eg. a delay), c) generate a cyclic clock pulse, d) accumulate run hours for a piece of equipment.

Use (5)function blocks for other logic, eg PID control, program looping etc. There are many different (5)function blocks for a wide range of functions...

Click to expand...

How to download the program inside Simatic S7 Manager ?

And, how to upload the program inside Simatic S7 manager ?

Also, why do we need to download & upload the PLC program ??

thanks

Someone else will have to answer your first two questions.

In answer to your third, sometimes we may make changes to the PLC program, the database, or the configuration when we are not connected to the PLC. Sometimes the changes are not allowed when we are connected to the PLC, so we have to do them "offline".

To get the new program with its changes into the PLC, we have to download it from the PC to the PLC.

Upload is simply the reverse of download - getting the PLC program from the PLC into the PC.

NB : Some manufacturers view of Upload and Download is opposite : In the Allen-Bradley world, Download is to transfer the whole program to the PLC : When working on a system, be sure you know which way the program will be going.... I hope you never find out the hard way !

Some manufacturers view of Upload and Download is opposite : In the Allen-Bradley world, Download is to transfer the whole program to the PLC...

Click to expand...

The terms have been thrown around loosely so that they have almost lost all true meaning. Downloading or uploading is relative to the system involved. It is like the theory of Relativity: time is only relative to the observer's viewpoint. Likewise, whether you are downloading or uploading depends on where you are standing, or on which computer you consider to be the observer's location.

To use either term correctly, you first have to know where HERE is: where the viewpoint is. If you are in a computer, then if you "upload", that actually means to move data from SOMEWHERE ELSE to THIS COMPUTER. However, because most people mostly only receive data to THIS COMPUTER from somewhere else (and from the relative viewpoint of that somewhere else, it is truly a "download"), then they mistakenly use the same terms that the origination site used, thinking that they are "downloading" when in reality they are "uploading to this computer" from a site which is "downloading to their computer".

We might as well face up to it: Downloading and uploading are going to cause as much confusion in the future as the infamous sinking and sourcing definitions. The reason is the same: the definitions depend on the viewpoints of the users.

In the case of Allen Bradley RSLogix and others, the viewpoint is that of the software program which resides inside the computer (not the PLC). Therefore, as used correctly by AB, an upload would be moving data into the PC, and a download would be moving data from the computer to the PLC.

Perhaps other brands consider the PLC to be the observer location, therefore the download and upload usage would be reversed!

Lancie1 said:

The terms have been thrown around loosely so that they have almost lost all true meaning. Downloading or uploading is relative to the system involved. ...........

Click to expand...

Nicely put, I usually simplify for my students.

The PLC is in a panel on the factory floor - you can't go any lower, so you have to go DOWN to it.

And then of course the syntax of language kicks in - do you say Download TO, or Download FROM.

For me its easy - always been around A-B - and I download FROM the internet/server, and download TO the PLC : upload FROM the PLC, Upload TO the Internet/server... i.e. I position my PC's viewpoint "in the middle", so if I "download" some sample code from the website, why would I think of doing an "upload" to the PLC, that implies a change of direction, i.e. sending it back to the website....

It must be hell for maintenance people who have to deal with different systems, and their manufacturer's differing viewpoints, and especially if they don't have to visit a piece of plant for months.

Perhaps if we could jettison the words Download and Upload, replacing them with "Transfer", then the directional words FROM and TO will always convey the necessary meaning..

Upload the PLC Program = Transfer FROM the PLC
Download the PLC program = Transfer TO the PLC

Upload an FTP file = Transfer TO the FTP site
Download an FTP file = Transfer FROM the FTP site

An interesting snippet from Wiki....

Wikipedia said:

Sideload

When applied to local transfers (sending data from one local system to another local system), it is often difficult to decide if it is an upload or download, as both source and destination are in the local control of the user. Technically if the user uses the receiving device to initiate the transfer then it would be a download and if they used the sending device to initiate it would be an upload. However, as most non-technical users tend to use the term download to refer to any data transfer, the term "sideload" is sometimes being used to cover all local to local transfers to end this confusion.

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