Rslogix 5 using 1771-db module how to write the program

Dear friends,

I am new this PLC 5 Series in that i need write the program for Analog Input and outputs using 1771-db(generic Module).Please give the suggestion for how to take the address in BTW and BTR.
how to assign the rack,group and module in BTW and BTR
find the attachment of my project io details

Hi aravindhcute,

The practice I was given many years ago suggests that I reshuffle your layout to show you an example as my attached file.

I have grouped the DB card, the analog cards and the 16 channel DIs together, with the high density cards in a separate rack, communciating using a 1771-ASB RIO adapter card.

Reason being that complex cards like IFE/OFE2(analogs) and DB(basic module) talk to the processor on the faster backplane, and you can use single slot addressing on an 8-slot rack (cards 0-7).
Then the high density cards are on their own rack with 1/2 slot addressing giving you rack 1 card 0/1, 2/3, 4/5, 6/7. rack 2 card 0/1, 2/3, 4/5. - another 8 slot rack.
You would then need a 1771-P7 power supply for the first rack, and could use a single-slot power supply (1771-P4S) for the second.

This would make a less-complex solution, and separates the low density and the high density cards.

It is a long time since I have set up a mixture of these cards and am unsure whether you can have them all in the same physical rack as you show it, and how they would be addressed, beacuse all slots would have tp be shown as 1/2 slot addressing.

I hope the above makes sense.......

Mr. Calderwood is correct that you must use "1/2 Slot" addressing mode in order to mix 32-bit and analog modules in the same chassis.

Because the 1771-DB is the first module next to the controller, it will be Rack 0, Group 0, Slot 0 in any addressing mode.

Writing BASIC programs and interfacing with the block transfer data is a substantial topic itself. Start with the User Manual !

Good luck with the programming of the 1771-DB module.

One of my first jobs as a system integrator involved programming 17 of these DB modules, each one needing multiple EPROM programs because the whole application didn't fit into RAM.

It was many years ago, but one thing sticks in my mind - DO NOT use two-letter variable names, e.g. BN (for Batch Number)... The compiler would occasionally corrupt these, causing the final program to crash.

I spent far too many hours proof-reading what the module had interpreted my program as, only to find it had "mis-read" the source code.

Please give sugestion

THANKS Mr.Ken Roach & JohnCalderwood

But existing program done manufacture they taken BTW and BTR for Analog Input and outputs for same Rack num(003) only can you explain how it possible.
I am attached the my Analog inputs and outputs BTW and BTR settings
so as per existing logic first analog input module BTR and BTW is taken as (rack003),(group 0,1),(Module-0) and 2nd Analog Input Module for BTR and BTW is taken as(Rack003),(group-2,3),(module-0),3rd Analog Output BTR and BTW is taken as(rack003),(group-4,5),4th Analog Output BTR and BTW is taken as (Rack003)(group-6,7),5th Analog Output Module if i taken Rack003 or else what i can take BTR and BTW is could you give sugestion for that

A better note regarding variables is that the variable names are determined by 1st letter, last letter and number of letters. Therefore, according to the interpreter, the following variables are THE SAME:

METER - MOTOR

I supported the DB for 3 years out of Highland Heights and used it for several years in the field. Don't remember a whole lot though. If I can be of help, please ask.

Good Luck,

Yosi