@sivamgr wrote:
While developing the component, I couldnt find much reference meterial on the internet at free of cost. rather, I used some network freeware tools and the partial information available in the following meterials to build the component. I did some crude reverse engineering on the packets sent by RS-Linx and PLC for understanding the concepts like vendorID and other parameters..,
I beleive that the code might require some work around. But, unfortunately I dont have access to AB-PLCs at this stage. I would appriciate, If anybody plans to optimize the code or to build a new component. The above reference might be useful to them.
As far as the relaiablity of those components concern, I am using these set of libraries in all my recent automation projects dealing with AB-PLCs. In one of the project that runs 24x7, the software reads 450 tags across 5 PLCs(MLX Series) every second. Its running here at bangalore (IFB Automotive) fine for the past 4 months with no crash reported till date. (Despite of the extensive usage of Build Array in the SubVIs)
For Communicating with CompactLogix, ControlLogix PLCs, the components available at this link might be useful,
http://forums.lavag.org/index.php?act=attach&type=post&id=6948 . This uses pure CIP (Command & Information Protocol / Common Industrial Protocol) Service Messages for tag access. Recently, I helped a software team to make use of it for a project at Delphi-TVS, Chennai. I am yet to receive any crash information from them.
I beleive that the DeviceNET Protocol is a simple Implementation of CIP over CAN. please correct me if I am inaccurate.
If the TCP-Open,Send, Close used in the EtherNET_CIP VIs are replaced with CAN Open, Send and Close then, it would be able to communicate with the DeviceNET supported devices. But unfortunately, I dont have enough resources to test the theory here at bangalore at my own cost. I would appreciate if anydoes check this out and brings out a component to communicate over DeviceNET.
Message Edited by sivamgr on 10-04-2007 10:16 PM
Hi everybody,
Please keep the below point in mind while using EIP Scan Register/Update Register
1) In EtherNet/IP, it cannot be read more than 90 registers in single read. This is because of the TCP/IP Packcet Size Constraint. The Scan/Update VIs would return a Data error in case it cannot get the values in a single TCP Packet. In case of bulk read/write, please perform a segmentised read/write
2) For Example, if you want to read 256 registers from N7 File, Do it in 3 steps
STEP 1: Scan (Offset=0, NoOfElement=90)
STEP 2: Scan (Offset=90, NoOfElement=90)
STEP 3: Scan (Offset=180, NoOfElement=76)
Best regards
Siva
sivamgr@gmail.com
