PLease help me..
- Thread starter mouzhin
- Start date
Ken Moore
Lifetime Supporting Member
not connected
You are not connected to the PLC, your are "offline".
You set down at your pc and write your code, you are programming offline. Then you download your program to the plc and place it in run mode. While observing the program running, you notice a minor mistake. You then edit the program while it is running, this is called "online" programming.
You are not connected to the PLC, your are "offline".
You set down at your pc and write your code, you are programming offline. Then you download your program to the plc and place it in run mode. While observing the program running, you notice a minor mistake. You then edit the program while it is running, this is called "online" programming.
brucechase
Member
I'm not sure what your instructor wants. Please read over your class notes and your text book.
jayesh.monpara
Member
- Join Date
- May 2005
- Posts
- 9
offline means you are working irrespective the conditions of plc.
In this mode, u make changes whatever u want and then download it to your plc.
Changes made in offline mode is the right way to do programming.
In this mode, u make changes whatever u want and then download it to your plc.
Changes made in offline mode is the right way to do programming.
Mickey
Lifetime Supporting Member
jayesh.monpara said:
Offline is not right or wrong. There is nothing wrong with online programming. Please explain your position.
SNK
Member
From what I can understand from your English,
Word length with respect to Resolution can only be compared to a Byte, 4 bits, a 8-Bit Word, or a 16 Bit word. Now there are 32 bit words.
The max resolution with 16 bits as an integer is 32768 (15th bit being the sign bit)
If you are using a 8-bit word, or a 12-bit word, your resolution of the analog input would not be as full as say a 16-32 Bit analog input.
I hope this answers your question.
This is in no way the most precise answer. You need to do a little digging for yourself in the textbooks.
Word length with respect to Resolution can only be compared to a Byte, 4 bits, a 8-Bit Word, or a 16 Bit word. Now there are 32 bit words.
The max resolution with 16 bits as an integer is 32768 (15th bit being the sign bit)
If you are using a 8-bit word, or a 12-bit word, your resolution of the analog input would not be as full as say a 16-32 Bit analog input.
I hope this answers your question.
This is in no way the most precise answer. You need to do a little digging for yourself in the textbooks.
??? what if you have to do a minor change and the plant is running?? Just tell everyone to take 5 while you download your program..To find out you made a boo boo and have to download again??..jayesh.monpara said:
New project i create offline but changes to existing i always do on line..
hi there everyone,
I agree, there's no right or wrong with online or offline programming. I have been using the online programming for quite a while already because our equipment needs some minor programs changes only. But it would be SAFER to do offline programming when major program changes are needed or should be done. What I mean is it depends on the situations or conditions you are up to.
I agree, there's no right or wrong with online or offline programming. I have been using the online programming for quite a while already because our equipment needs some minor programs changes only. But it would be SAFER to do offline programming when major program changes are needed or should be done. What I mean is it depends on the situations or conditions you are up to.
I am working with 64 bits these days.
Bit archaic. I do lots of online programming quite frankly. Even with the PLC 4500 km away by modem. Use Norton pcAnywhere and take over the computer. Paricularly masses of code for generating information for SCADA systems but also extensive changes to code controlling generators and swimming pools.
IEC word types include
UINT unsigned integer (16 bit with no sign = 4095)
INT signed integer (16 bit signed = 2048)
ULINT unsigned quad integer (64 bit unsigned = 4294967295)
LINT signed quad integer (64 bit signed = 214783648)
UDINT unsigned double integer (32 bit unsigned = 65535)
DINT signed double integer (32 bit signed = 32768)
REAL 32 bit floating point
LREAL 64 bit floating point
Then there are BCD types etc.
Leadfoot
Member
mouzhin said:
Resolution when used with analogue inputs/outputs usually refers to the scaling of the input and output.
Like you have 0 to 5 volts in and need 0 10 volts out.
Additionally, as was mentioned, internally you usually have internal values such as the 32768 bits to use to scale the inputs and outputs.
Analogues are great in that you can use current in and get voltage out or voltage in and current signals out.
elevmike
Member
The higer the number of bits the higher the resolution:
8 bits = possable values from 0 to 255
16 bits = possable values from 0 to 65,535
So your analog input might be a 4-20 ma 8 bit input. That would mean that as 20 ma. Your PLC would see 255. However if its a 16 bit module the top value would be 65,535.
Imagine a 1 meter ruler with only 100 CM marks on it (low resolution). A high resolution ruler would have 10000 mm marks on it. Your measureing the same lenght but with smaller graduations. A higher resolution 16bit analog input would be far more accurate then a low resolution 8 bit unit.
8 bits = possable values from 0 to 255
16 bits = possable values from 0 to 65,535
So your analog input might be a 4-20 ma 8 bit input. That would mean that as 20 ma. Your PLC would see 255. However if its a 16 bit module the top value would be 65,535.
Imagine a 1 meter ruler with only 100 CM marks on it (low resolution). A high resolution ruler would have 10000 mm marks on it. Your measureing the same lenght but with smaller graduations. A higher resolution 16bit analog input would be far more accurate then a low resolution 8 bit unit.
STEVEBOT
Member
Having Worked With New And Old I Do Online And Offline Programing. With The Newer Versions Dowloading A Program Is So Much Quicker Actually Stopping A Machine To Download Is Done In Circumstances Where Actual Danger Are Forseen As A Possibility In Other Words Planned Stops.
Most Changes Are Quick Tweeks That Are Done Online
Most Changes Are Quick Tweeks That Are Done Online
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