COM Profibus/TI505

[garrettj]

Hi

The project I am working on has purchased a 555 processor (actually the new CTI 2500 -300 CPU) and all the IO is to be profibus - of the S7-300 (IM153) type. I have done this before - with digital IO only.

My question is - when you put an Analog Input of RTD Input card of the S7-300 type - how does it appear in your program with regards to PLC counts. Native 555 IO cards would be 6400 - 32000 or 0 - 32000 for an RTD card. If these were native in a Step 7 program that would be either 0 - 27648 or an integer in the case of the RTD.

What happens in Com Profibus? Do you get the choice to scale these inputs?

I know when you use Com Profibus with digitals they appear as X's and Y's just as per normal - i.e. as if they were TI IO.

Thanks

Jason Garrett

 

[Ken Moore]

I haven't got my hands on the 505 replacements from CTI yet, but when I've had any issues with the CTI communiction cards there tech service has been outstanding. I would suggest you contact CTI, since they built the processor, they should be able to answer your questions.

 

[Tresco-oz]

Hi Jason

I'm not sure if there is a standard for Profibus analog inputs, we have a 545-1106 CPU talking to some MTL8000 I/O, it returns 10488-52488 on analog inputs over the range of 4-20mA. We use a SFSUB in the 545 to convert these values into 6400-32000 range.

regards
Phil McKay

 

[grunt]

siematic profibus analog i/o

I have used many CTI and Siemens analog input and output modules over profibus. They were all configured for unidirectional 0-10vdc or 4-20Ma = 0-32000 and as a wx or wy.

 

[Dua Anjing]

What we do here is in the Ti PLC we "fudge" or offset the SCALE/UNSCALE. In a "normal" Ti you might scale an AI 0 -100% with S7 I/O you can scale as 0 - 116% (unsure of exact amount but it was around 16% extra) that way when SCALE instruction reads raw value of 27648. It is scaled similar to this..
SCALED VALUE = (RAW_VALUE/32000)* SCALED_MAX(116).