Omron PLC Center

We should begin, as always remember to join, that is a plc plc plc … In other words, to understand the theory, and then find out how our producer of choice “makes it work.” Some manufacturers are RS-232 communications capabilities in the main processor. Some use “programming harbor” for these. Others need to spend to buy (ie an extra $ ’s) to speak a module “RS-232″ with an external device.

What is an external device, you may ask? The answer is difficult because there are so many external devices. It may be a user interface, an external computer, an engine controller, a robot, a vision system, a … Get the point?

To communicate via the RS-232, we have put a few things. Ask yourself the following questions:

How will the data warehouse, we store the data to be sent? Mostly we have had to store the data, we … somewhere. Where else but in our data store!
As the data warehouse is, we are the data that we receive from the external device?
How will we tell the PLC when it’s time to be sent to us, our data (data stored in the data warehouse) via the serial port?
How will we know when we have received the data from our external device?
If you know the above, then you can rest easy. If you do not know the above to do something, and be reassured. Huh? Simple, select a region of memory to work with and to find out if we can choose to use the internal relays, to send and receive data, or if the PLC has she provided for this purpose. Sounds too simple? (No, it’s easy!)

Before we do, so let’s get some more technical terms of the way so that we are on the same playing field.

Buffer A buffer is a word that means a plastic bag technical imagination. In other words, it is a temporary storage place, where the PLC or peripheral device stores the data it has received (or waiting for transmission) via the RS-232.
When I go to the supermarket to buy my favorite TV dinner, I carry them home in a plastic bag.
The bag is not a permanent place for my food (as a TV dinner real food?), But rather a temporary storage place for them until I get home. When I go home I get them out of the bag and cook.
Supermarket was the external device where I is the information (TV dinners) of my microwave plc. The bag was) buffer (temporary location, which kept my data (TV dinners), until I took them (ie use of the cooking).

A String is a cool way to say “a lot of character.” The word “Hello” is a string. It is a set of characters (eg hello), connected (preferably together), to mean something useful. “43,770″ is also a string. Although it makes no sense for us, may mean something of value to your PLC or external device. It could be a command that tells your bot to send their current coordinates. (or it may simply the word “hello” upside down)
Concatenate-This word has a mouth full. Simply put, this means a combination of 2 strings together in a string. One example is the 2 strings combine “laser” and “Jet” together to make a string … “LaserJet”.
With jargon out of the way we see them in action. Again, the slots and relays the manufacturer varies, but the theory is universal.

We distribute slots DM100 by DM102 to be where we will put our data before we send the serial interface. Note PLC Many have dedicated storage areas for this and only for that purpose.
We have internal relay 1000 for our forward relays. In other words, if we us 1000 plc, the data in DM100-DM102 the serial port to send to external device. Note again have many PLCs relay (special software relays) paid for this and only for that purpose. It’s amazing when the manufacturer makes our life easy!
We send the string “ALR” Next plc serial interface to a user interface when our temperature sensor input is activated. This means that our oven was too hot. When the panel receives this string, it displays a warning for the operator to see. Search Back to the ASCII chart and you will see that they are “ALR” is hexadecimal 61, 6C, 72 (a = 61, L = 6C, r = 72) We write the ASCII characters (hexadecimal) of the individual memory locations . We will DM100-102. How? Think of the LDA or MOV instruction? We will continue to relay (1000 revolution), where a temperature sensor switches (0000) in if required. The ladder is shown below.

Certain PLCs may not have dedicated internal relays that send our data through the RS-232 port. Maybe we need to manually assign. In addition, some PLCs have a special instruction to tell us, where data is stored and where to send data. This teaching is often seen as AWT (ASCII Write), or RS. The theory is always the same thing himself. Load data into a memory location, and then send a relay data.

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