Data Capturing

Hi guys. Just like to find out whether PLC is capable of capturing data and displaying them at a later date. For example, the plc is able to note down when the machine is stopped and when the machine is started. If it's possible, then how do i go about doing it and what are the things that i need?

regards
merry christmas and happy new year

Database

Hello
Many PLCs has database in different sizes
The database of the PLCs I know is divided into part which is on the flash memory and part on the RAM.
To the database on the RAM one can send data while the PLC is running and actually log information.
This information can be any binary value and usually also strings.

Different PLCs are different in the way they relate to the database (my PLC allow for example to configure data tables like in MS Accesses) and you should check the differences according to what you need to store, the volume and the level of interaction you need to a PC (send data out to a PC based application).

If you want specific information I'll be more then happy to help

Avner

First, you need a PLC with an internal clock/calendar function. In addition your PLC needs either a shift register function or a FIFO or LIFO funiction, or a way to do indexed addressing.

Whichever function you use, set up two banks of data registers, one for the time when the event occurs, the other for a code that tells you something about the nature of the event. For example, a value of 1 might be the code for starting the machine, a value of 2 might indicate stopping due to operator command , 3 might indicate stopping due to a jam condition, etc.

Whenever an event occurs that you need to record, copy the time into the first available element of one bank of registers, and write the code into the corresponding element of the other bank of registers.

Database

Hi guys. thanks for the reply so far. Avner, do u mind giving me the specific details? I'm totally new to this database thingie. Steve, how do i write a program that can achieve what u've said? By using laddre logic? Should not be.. BTW, have you guys heard about a PLC company by the name of Trilogy? are their plcs any good? can their M series PLC achieve this function?

REgards

Depending on your system, there may be an even easier way. Many operator interfaces have both a real time clock and an alarm log. The alarm log will monitor a bit in the PLC, and if you set it (turn on the coil with that address) the operator interface will save the event to a log, and include a time and date stamp. This is the way we usually accomplish what you want, as it involves minimal programming.

huh? then what if i'm using a M series PLC from TRILOGY (http://www.tri-plc.com/) anybody used this type of PLC to attain such a function before? IF cannot, then what type of PLC should I use?

regards

I'm not familiar with that brand. They do show Modbus on their site, which most interfaces work with. They do list EXOR, which we use for the alarm logging functions I described on a lot of different platforms. You may want to talk to the manufacturer and find out what other communications protocols and opertor interfaces they support.

As both Tom and I have indicated, it is possible to use a PLC or a PLC/HMI combination to do what you want. However, the details of actually doing it depends on the model that you're using and your experience level. It is certainly a task that goes a bit beyond basic ladder logic, timers, and counters.

Our explanation of how to approach the problem is nothing more than a road map to help you get to where you want to go. If it seems like more than you understand, given your current experience level, then you might want to consider hiring someone to do it for you, and following that person's progress so that you can learn how to do it yourself next time.

Event Log

Hi

As Tom mentioned, using the EXOR (or any other) HMI will do the trick.
When I considered using EXOR the first time, I have got comprehensive assistance from the local dealer. Using this HMI is almost intuitive, and once you assign the bits to be flaged by events, the HMI program leads you through the rest of the tasks.
You may want to visit EXOR's web site for more info

http://www.exor-rd.com/Products/

Thanks for the advice everyone. have been told that i'm able to write the data to the plc's eeprom and retrieve it at a later time. but the eeprom is a bit small because it can only store 16 address. don't u guys think so? anyway, really grateful for all the advice.