Remote Warm Start an AB PLC5


Thread Starter

Vincent W H

Hello all, Could anyone teach me how to warm start a AB PLC5 via Ethernet with Excel or Visual Basic not AI or Logic 5. Thx.
I think what you are asking for is to turn a PLC-5 from Remote Program mode into Remote Run mode by poking some location in memory with RSLinx and an application you write. Unfortunately, it's not that simple. Excel and VB can command RSLinx to perform certain types of communication commands to read and write data to the PLC-5; generally these are Word Range Reads or Word Range Writes. (yes, I'm simplifying). But to change the PLC-5 mode, you send a low-level command, not a data request. RSLogix reserves that privilege to itself because you can control the access levels of RSLogix users. Many plant managers tell us they don't want rogue spreadsheets shutting off or starting controllers. I expect it is possible to use the PCCC transport mechanism in the C software developer's kit for RSLinx to send the proper low-level command, but you will find that A-B considers that data proprietary. It's probably best to find a way for the user who needs to do this to check out an RSLogix activation from a file server and run that remotely. Ken Roach Rockwell Automation / Seattle [email protected]

Anthony Kerstens

What precisely do you mean by "warm start". I've never come across that term in relation to a PLC. You don't mean "warm boot", do you? Anthony Kerstens P.Eng.
Hi Vincent: If you know how to read C code, you might check out my ABEL library (Allen Bradley Ethernet Library). While my code is wrote around a POSIX environment, the basics are there and should be quite understandable as far as how to construct the command packets and how to interpret the reply. The library may be downloaded from: By the ways, by warm start, do you mean switching the PLC from PROGRAM to RUN mode? -- Ron Gage - Saginaw, MI ([email protected])
Hi, Warm Start is nothing but restarting the PLC with the application program already loaded into the RAM, Warm Start is also referred as Warm boot, Hot Init etc., Whereas Cold start/Cold Init is nothing but starting/rebooting the PLC with clearing the application programs residing in the RAM.