GE Veramax vrs. RSLogic learning curve

I have been programming with Allen-Bradley processors a number of years now. I will soon have a job which I must use a GE processor (CPU001, MDD845).
My question is how much learning curve should I expect or is it basically a ladder diagram is a ladder diagram.
The GE will have some analog inputs and outputs for controlling water temperature, a counter module for flow totals and some digital inputs and outputs for valves.
It's a fairly simple program that I could almost do with my eyes closed using RSLogix.
Anyone went through this learning curve before?

GE Versamax vrs. RS Logix

I should have checked my spelling first, sorry.

The addressing is different. Rather than having addressing determined by the physical location of modules, you assign addresses to each module using the hardware configuration tool. Inputs are %Ixxx, outputs are %Qxxx, analog inputs and outputs are %AIxxx and %AQxxx. Numeric data from the HSC will be located in %AIxxx registers.

Instead of timer and counter files (T4:xx, C5:xx), each timer or counter in a GE uses three consecutive %R register addresses, %R101, %R102, %R103 for example. The first of these three is the equivalent of the AB timer's .ACC value, the second is the same as AB's .PRE value. GE's timers and counters don't make the .EN, .TT, or .DN bits readily available in ladder logic. For the .DN bit, you program a coil at the output of the timer function block, and use contacts from it.

If you need floating point math, instead of an F file, you specify REAL as the data type when you program a math function. This will automatically use two consecutive %R addresses (32 bits).

The consecutive %R address technique leads one of the most common problems that people get themselves into with GE processors. You program a timer using %R1, then program another timer using %R2. Now the addresses %R2 and %R3 are used by two different timers, and neither timer works properly. There is an easy way to avoid the trap. When you enter the address for a timer, instead of typing in the full address (%R25 for example), simply type in '%R' leaving the specific address blank. The programming software will pick the next available %R address for you.

Hope this helps.

Thanks, Steve

Thanks for info on the addresses, especially the part about the timers.

When I used GE PLCs in the past, I didn't like the feature that allowed the next available address to be selected automatically, so I made sure I declared the variable addresses explicitly for anything with a word length > 1. For example: %R1 would be assigned to a timer, then %R2 and %R3 would be explicitly defined as belonging to that timer. This allowed me to set up the memory map like I wanted and prevented overlapping addresses.

I could have done a better job of explaining about the next available register.

When you assign a register (say %R101) to a timer instruction, the programming software will set the 'highest register used' pointer to that address plus two (in this case %R103), so that the next time you ask for the first available register, you'll get %R104.

The technique will not fill in 'holes' of available registers. It only keeps track of thre highest usage. It works for all memory types, not just registers.

I personally prefer the GE programming to Allen Bradley. EAch has its strengths and weaknesses, and each has quirks. In my case I went from other brands (Koyo and Misubishi) to GE, and then to Allen Bradley - no major hurdles, and I think the GE is more intuitive and logical. I don't think you should have too much trouble making the transition.

I came to AB from GE. I used to program with LM90.
I must to say that AB for me is more logical and easy to use.
I forced to do some machines with VersaPro and I didnt like it at all.
I think RSLogix is some step above VersaPro.
If I can chose I would prefer LM90 insted VersaPro.
After some years of PLC programming I think Omron Syswin is my first choice then RSLogix then LM90.

Its funny, I spent most of my time learning on AB using 6200 then going to RSLogix. This thread made me realize somehting...I have never actually programmed an AB I have modified programs or used to troubleshoot ALOT but never a start to finish program.

My first PLC to actually program was a 90-20, GE's micro line at that time. Since then I have done alot of GE 90-30's using first LogicMaster 90 then VersaPro. I can state emphatically I never liked either, VersaPro didnt offer much over LM90 in many ways. The online issues are confusing...it partially allows editing and I get confused when I can and cant.

I now (but not for long) work with HORNER PLC'S, a third party vendor for GE. Its my understanding this may change in the near future. These use a program called CScape that is almost identical to GE's...ie the addressing and instructions are almost identical...down to the %. CScape is free though so if you want a program to download to get the feel for GE it may do the job. The place I work at was the beta site for the OCS line of Horner PLC's.

I aint the sharpest knife in the drawer but if I can program a 90-30 I have no doubt you will find it easy especially if you are using the newer line of software, CIMPLICITY. Its my understanding GE stepped it up a notch and made an exceptional product...maybe one day I will get to work with it.