Making an array of I/Os in Rslogix 5000

[derama2 0]

Hi, I'm trying to map addresses in Rslogix 5000 to be able to communicate data in a PLC-5 format. I understand I need to create arrays of the data to map the addresses, and I have having issues creating arrays of the I/O. I have mostly digital inputs and only 2 analog input points. I'm not very familiar with RSlogix 5000, does anyone have any advice or am I on the completely wrong track? -Cindy

[Bill Linne 0]

Cindy: Simply create a tag in the Logix processor of the data type INT, and make it whatever length you need to handle the data points. For example, if you need eight words of digital data (these are 16-bit words) and two words for your analogs, your new tag would be ten words in length (when you create the tag, the box for assigning one of the dimensions is greyed-out, the other is not). In the box not greyed-out, enter 10. So, now we have New_Tag, which is ten words in length. You will refer to these words as New_tag[0] through New_Tag[9], and at the bit level, New_Tag [0].0 through New_Tag[0].15 (and so-on). Now to populate these words, you can either "map" them in ladder logic bit-by-bit, or assign hardware inputs to them directly (in the tag editor). How you message the data to the PLC-5 depends on what "drives" the need for the data. If simple timed updates are okay, you can read this array from the PLC-5. Establish a MSG instruction in the 5 as usual, but in the Target PLC data address field enter "New_Tag[0]". Important: The quotation marks must be included! This is a bit of a work-around to the documented need to establish a data table of all tags you intend to communicate to PLC-5's. So, after the target field is filled-in, enter a length of 10. This will be a multi-hop message with the usual formatting for getting from the communication module (an Enet module, probably) to the slot where the processor lives. If you need help with this, I have more details at the shop, just "holler". If the need to send data to the PLC-5 is based on something happening at the source end, then your MSG instruction should be a Write type and live in the Logix processor (and obviously conditioned to execute when whatever-it-is changes). Note: Read type messages are more efficient than Write type messages (less network overhead and housekeeping). Note: I usually establish my source arrays at a length longer than I really need. Then, if I need to communicate more data to that particular PLC-5 in the future, just increase the number of words the MSG instruction is reading (or writing); no need to take either processor out of RUN mode. Just be sure to leave room for expansion at the destination, too. Hope this helps. Bill