Skip to Content

Register Login

Industry Online Support

Technical Forum

Navigation

What the different between 'M' memory and shared DB?

Created by: christer007 at: 3/10/2006 2:00 AM (4 Replies)

Rating (0)

Thanks 1

5 Entries

3/10/2006 2:00 AM	Rate (0)
christer007 Posts: 5 Rating: (0)	We are using memory area to store our program intermediate result, which one is better. What will happen if the program in CPU313C wants to turn a value(say, PID_out) up and the operator are tuning down PID_out in MP370 at the same time? Which one has priority? Thanks a lot.
christer007 Posts: 5 Rating: (0)
Suggestion To thank Quote Answer

3/10/2006 2:47 PM	Rate (0)
Chris Silver Member Joined: 8/31/2005 Last visit: 10/24/2024 Posts: 217 Rating: (41)	Hi christer007! [quote user="christer007"]We are using memory area to store our program intermediate result, which one is better. The question if bit memory "M" or shared DBs ar better is a quite philosophical question. If you have only a little amout of data to store it doesn't matter, which memory you use (Maybe there are some differences in the access times to the memory - I don't know exactly). If you have a large amount of data it is better to use DBs, because you can structure you data into different DBs. [quote user="christer007"]What will happen if the program in CPU313C wants to turn a value(say, PID_out) up and the operator are tuning down PID_out in MP370 at the same time? Which one has priority? It is not possible, that a value can be accessed at the same time by the operating system and the user. There is always a little time lag between these two events. And the last event is setting the value. But if the operating system is writing this value (PID_out) in every cycle, the user input is always overwritten one cycle later.
	Greetings, Chris
Suggestion To thank Quote Answer
This contribution was helpful to 1 thankful Users DLittlejohn412

3/22/2006 10:51 AM	Rate (0)
crazysiemens Posts: 2 Rating: (0)	I think I say I know ,if the power is off,M memory will set to zero or false. DB can hold the last data before the power is lost.
crazysiemens Posts: 2 Rating: (0)
Suggestion To thank Quote Answer

3/22/2006 4:36 PM	Rate (0)
Chris Silver Member Joined: 8/31/2005 Last visit: 10/24/2024 Posts: 217 Rating: (41)	[quote user="crazysiemens"] ...if the power is off,M memory will set to zero or false. DB can hold the last data before the power is lost. You can also set M memory to be retentive (via the HW config), so there is also no data loss, when there is a power failure.
	Greetings, Chris
Suggestion To thank Quote Answer

3/22/2006 6:01 PM	Rate (0)
gre_m Posts: 947 Rating: (45)	M-memory is fastest. Size M-memory defined type CPU - see catalog ST70
gre_m Posts: 947 Rating: (45)
Suggestion To thank Quote Answer

|

Share this page:

Share this page on...

Follow us on