Program Addressing Question

When would you use a bit address as B3:62/10, O:0.3/5, or I:4.1/2 instead of using the whole word as B3:62, O:0.3, or I:4.1? Which is the correct method used for addressing actual outputs such as
O:0.3 or O:0.3/5 "Turnstyle Rotate CW"? I am using Allen-Bradley RSLogix 500 and converting a legacy 5TI program. Thank You

Is this a joke or trick question?
Do you know what states bit can have?
Do you know what states word can have?

I hope I understand your question,

When dealing with inputs and outputs, you rarely want to address the whole word, as this would mean that you are reading all the inputs or outputs at once.

For a 16-terminal Output-Card:

O:0.3 (word) - means all terminal points 0,1,2,3 through 15
O:0.3/5 (bit) - means only terminal point 5

The same goes for inputs.

For a 16-Terminal Input-Card:

I:4.1 (word) is all terminal points 0,1,2,3 through 15
I:4.1/2 (bit) is just terminal point 2.

Most of the time you will just use the bit, but using the whole word can have its advantages...

For example if you want to know if all the inputs are off, you could make a rung with 16 instructions, each testing one of the bits..

or,

you can use one EQU instruction, and test if the whole word (I:4.1) is equal to zero.

No, this is not a joke or a trick question. I am just someone new to programming and re-writing ladder logic. I have posted this question here since I was unable to find the answer or material pertaining to this question via the Internet, hardcopy, or PDF manuals. I understand that a word of 8 to 32 bits can have many different states.

Panic Mode- The top of the screen says "PLCs.net your personal PLC tutor site" Granted the question is a basic one, but it is not out on line.

mbd0722-
Just to give you some terminology.
bit=1 or 0
byte= 8 bits
word= 16 bits
longword= 32 bits.

As others have noted, devices which have ON/OFF states only take 1 bit as an input or output. Analog devices typically take up a full word of the inputs or outputs and are addressed accordingly.

Am I correct in writing that I could assign Input word I:4.1 to 16 different inputs and Output word O:0.3 to 16 different outputs and if desired test all these bits with the EQU instruction for verification or monitoring? Could these same input and output bits be individually assigned to internal memory for processing in various subroutines of the program using as an example words B3:62 and B3:63? Thank you for your responses and terminology. I am starting to understand.

As noted by Dave, the inputs and outputs are 'assigned' by picking the input/output cards, inserting them in a certain rack and slot, then wiring the input or output to a certain pin. In general you don't have any further option to directly re-assign their address. Once this is done you can directly use this reference as often as you wish throughout the program. You certainly can copy the input bits to other 'B' file references, but there is no need to do so.

Yes

Yes MBD, you can write a one in every output on a card if you want, we do here for testing lamps on consoles.

Also, there are times you will need to copy the whole word from an input or output card to a binary word if you want to use certain EZTouch panels with some of the Allen Bradley SLC Processors.

Thanks for the clarification on the unnecessary use of B file binary elements. I will save the B files for the TI program's CR and MCR conversions. I am using the B files to replace the MCRs due to the differences between AB and TI MCR zoning rules.

I am not sure of the complete process but would the PLC be transmitting or receiving a complete word in binary BCD to or from an EZTouch panel in order for the touch panel to decode the word and display the correct message and or activate the correct device? I will be installing three AB PanelView 300 Micros.

Mill Maintenance is a very good idea.

I have yet to program my latest toy, a panelview 1000e, but the EZtouch needs those bits since it can't write directly with I/O on a few SLCs. So you copy the I/O to Binary in order to use the PLC with the EZtouch.

For example, you would copy the whole input word to an entire binary word in order to read inputs from the PLC on your touchscreen.

Don't discount the bits in a "B" (Binary) file. It is very useful to use them as a flag to indicate the status of a compare or a combination of input values. It is also useful to use bits in a binary file for reading and writing from an operator interface. You can then use the bit to turn on a single output.

Also, there is a MCR (Master Control) function in Alloen Bradley PLCs that you can use to bypass "zones" of the program without having to put a bit in each rung. Look at the RSLogx help file.