Zubair  Ahmed

Mitsubishi GX Developer

15 posts in this topic

Hello all ... i am a new plc user.. i am using D500 for taking value as it is a latched register. 

i am taking value for a flow meter. i have two questions.

1. how totalizer is calculated from flow rate as my flow rate is in m3/h.

2. the value of register is gone upto 32000 approximately... i want that this value to go on.. i mean how 32 bit register is declared in plc .. a

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What communication from flow meter to send flow rate to PLC(Analog Input, High Speed Counter or Modbus)?

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Is D500 that have 32000 is analog input or not? If yes, Analog Input will have raw input value should be 0 - 4000 (4-20mA) then it is 16 bit register that not necessary to 32 bit

but if I you need to use 32 bit register for another register you can add D prefix to function that you use it in 32 bits such as DADD DSUB DINC

Please describe for more information (PLC Model CPU, PLC Analog input Module, Flow meter datasheet, etc.)

Edited by Wasan

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according to transmitter output i have taken raw value for analog .. the raw or digital value then i compare and insert all values for transmitter to register.

i have just limitation to over flow.. when i use d500 as it is a 16bit register.. i just want to use 32 bit register.. and dont know procedure.. also help me out to find totalizer..

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I see then I have attached some example about 16 bit and 32 bit operation.

For 16 bit program you use 1 word to collect Result Data(D10, D12, D500)

but in 32 bit you can use same function but perfix "D" to use it as 32 bit function and manage address to 2 words(D10-D11, D12-D13, D500-D501)

FX_32_bits_01.jpg

Edited by Wasan
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you cleared alot .. but i want to know one thing. my values in register in case of total .. for example if we add d10 d12 d12 then d12has total values... when if we add and add .. then i want d12 has to stored more value.. will a 32 bit operation work for me or not..

Untitled.png

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add d400 d500 d500...  i am making d500 as a total flow that has been read by flow meter. .so d500 should store a alot value.. how can i do that.. i mean d500 as 32bit

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You can use D400(16 bit register) add with D500(32 bit register) it result will be D500(32 bit register)

--|M8000|----[DADD D400 D500 D500]------

FX_32_bits_02.jpg

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OK.. JUST FOR knowledge.. 32bit register can store value upto 2(power32) right?

 

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what is the differnce between 32 bit signed and unasigned number... also the value according to your ladder diagram is signed or unasigned stored in d500

 

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20 minutes ago, Zubair Ahmed said:

OK.. JUST FOR knowledge.. 32bit register can store value upto 2(power32) right?

 

Yes

15 minutes ago, Zubair Ahmed said:

what is the differnce between 32 bit signed and unasigned number... also the value according to your ladder diagram is signed or unasigned stored in d500

 

For Mitsubishi PLC you can monitor in signed decimal 32 bit. signed and unsigned decimal are difference at

32 bit unsigned decimal have value in range 0 to 4,294,967,295

but 32 bit signed deciaml have value in range −2,147,483,648 to 2,147,483,647

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Thanks friend.. you have provided me a lot of help.. you are true life saver.

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issue with totalizers is that results grows and normal data storage in PLC has limitations (32-bit register size for example,). real numbers have  larger dynamic range but set of own peculiarities (fewer significant bits etc). this means that exact implementation will depend on application and you did not provide any hard data or constraints so it is unlikely that any offered solution will be fit for your application.

one simple totalizer is to use clock of sufficient rate (1sec for example). then on a rising edge of that clock add current measurement to a total. that's it. to interpret data, scale it accordingly taking into account sampling rate.

 

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