Setting up an S7 connection using TCP/IP

The TCP/IP method of communication to the S7-300 and S7-400 PLC's via TCP/IP communication module uses the S7WIN, S7WINSP, S7NT, or S7NTSP protocol.

The Allen Bradley Logix5000 family (ControlLogix, CompactLogix, FlexLogix, SoftLogix) has some very good manuals. If you are just starting out or need a refresher here are the key manuals and the order I would read them. If you have RSLogix 50000 installed then you will find some of these in the Help > Online Books menu. Revision 16 also has some great videos in the Learning Center.

If you are a Siemens PLC user then you've more then likely have run into Statement List (STL) programming. STL corresponds to the Instruction List language defined in the IEC 61131-3 specification. The programming is done with very simple mnemonics that can be hard to remember if you don't use it very often.

These cheat sheets provide a quick reference guide for all the instructions and formatting. They are two pages long but if you can print on the front and back then they make for a nice one sheet reference.

Tags are the method for assigning and referencing memory locations in Allen Bradley Logix5000 controllers. No longer are there any physical addresses such as N7:0 or F8:7 which use symbols to describe them. These have been replaced with tags which are a pure text based addressing scheme. This is a departure from the more conventional ways of programming PLC’s, which includes Allen Bradley’s earlier line of PLC5 and SLC 500 controllers.

Courtesy of: Delta Automation, Inc.

The default setting for the remote I/O hold up time (HUT) on a Modicon PLC system, is 300 milliseconds. This determines the amount of time that the discrete outputs associated with a particular drop will remain in the "on" state once communication with the processor is lost. This loss can be due to a power loss at the drop or a cabling problem for example. With the default setting of 300, the discreet outputs will de-energize after 300 milliseconds (0.3 seconds).

Courtesy of: Delta Automation, Inc.

It is important to keep in mind when deciding the routing paths for your data transmissions which utilize more than one Modicon Bridge Plus device, the amount of traffic which may attempt to flow through it.

Courtesy of: Delta Automation, Inc.

Modbus Plus is a robust network of peer to peer communications used on process control and data acquisition applications, but several basic mistakes are commonly uncovered during the certification process performed by Delta Automation, Inc.'s Field Service Engineers.

Programmable Logic Controllers: An Emphasis on Design and Application author: Kelvin T. Erickson rating: asin: 0976625903 binding: Hardcover list price: $100.00 USD amazon price: $100.00 USD

Jeremy Pollard at Control Design Magazine gives this book a glowing review . That's good enough for me to add it to our recommended reading list.

The PIDE (Enhanced PID) is an Allen Bradley Logix5000 family (ControlLogix, CompactLogix, FlexLogix, SoftLogix) function block that improves on the standard PID found in all their controllers.  First impressions of this function block are quite intimidating.  If you try to dive into it head first you may just end up banging your head against a wall.  Many will be quite happy to stick with the tried and true PID instruction but to compete with the more advanced process control applications the PIDE boasts the following.

Rockwell Automation unveiled some significant additions to the Logix Control Platform at the Automation Fair event in Baltimore on Oct. 25, 2006. Further additions and improvements were detailed in a presentation on RSLogix5000 Version 16 as presented below.