PLC 5 - Block Transfer Write. How do they work ?

[Rob S.]

I really need to wrap my head around a PLC-5 , Block Transfer Write.
I am dealing with some alarm issues with a PLC 5 and Panelview Plus. I want
to understand how and where these alarms are being displayed on the Panelview Plus. It seems like alarms have the same method that most everyone is doing , but I just cannot track down how these alarms are being displayed on the HMI. Below is what I believe is shifting this alarm information.

BTW
Module Type - Generic Block Transfer
Rack- 006
Group - 0
Module - 0
Control Block - BT9:50
Data File - N95:0
Length - 32
Continuous - No

Could you please explain the above information and what it's purpose is in this BTW instruction ? And also what the common theory and or method is with alarming and HMI's .

Thanks so much.

 

[Ron Beaufort]

see if the "mailman" analogy helps ...

http://www.plctalk.net/qanda/showthread.php?p=16077&postcount=3

in your situation, your PanelView has already been addressed as Rack- 006 ... Group - 0 ... Module - 0 ...

think of this as the address on the envelope that the BTW mailman is delivering ... something like 123 Easy Street, Apartment A ...

the Control Block - BT9:50 is a location in the processor's memory where the address (etc.) is stored ... this part does NOT get transferred - it just holds the information required to tell the mailman how to make the delivery ...

the Data File - N95:0 is the STARTING point of the actual block of data which gets TRANSFERED ... so N95:0 through N95:31 (a total of 32 words) of information is INSIDE the envelope which the mailman is carrying ...

Length - 32 tells you how many words of information are INSIDE the envelope ...

Continuous - No ... this is usually set for NO - and then we use something like the Done bit of a Timer to "trigger" the mailman into operation ...