I am using MB_CLIENT to poll from a 3rd party device. I am only interested in 1 out of every 100 modbus registers (40003, 40103, 40203, etc). I have it set up and working as a sort of loop that polls 1 register, waits until the status is "done" and increases the requested address by 100. The problem with this is that it takes so long! I think the 3rd party device I'm working with is what slows it down. Right now it takes 12 seconds to poll 32 registers and that's not acceptable for the application.

One solution would just be to poll ALL of the data at once, but that's 100X more data than I'm interested in and I'd have to store and manipulate a ton of stuff I don't want.

Is there a way to use a single iteration of MB_CLIENT to poll specific non-sequential addresses?

Please let me know if there is anything I can be more clear on.

Thanks,

Amanda

Hello,

in case of enough available resources on CPU, you can try set new connection and in one time poll other range of devices via independed connection ID. Via this try cut your Servers IPs to required ranges, each range for available independed connection ID. This is only idea how to quickly solve your problem also, but of course in case of one device (Server) question is, if it support more connections at one time.

I haven't tested yet if the server supports multiple connections, but I don't think I want to chase down that path because I want to poll 99 registers and I don't want to set up 99 instances of MB_CLIENT (if that's what you mean -- I may have misunderstood).

It sounds like the best way will be to poll all of the data at once and then sift through and get what I want.

I think the best way will be to somehow get all of the data into an array and then do a FieldRead loop to grab 1 out of every 100 elements of the array. Now the question is: How do I get data from a modbus poll into an array? I believe the pointer for MB_CLIENT has to be a DB with 10,000 word variables. Can I somehow convert that to an array of 10,000 elements?

Thanks for your help,

Amanda

EDIT: Now I think your suggestion was not to do 99 instances of MB_CLIENT but rather do a few that each handle several polls. I like this idea, I will try it!

FYI -- this works perfectly! I have 2 connections going now and it cuts the time down by about 50%. I'll throw in a few more. Thank you for your suggestion!

Amanda

Amanda,

I'm having difficulties to work with Modbus on Siemens and I did not understand what you did to make it works.

Can you please send me a sample of what did you made? It will help me a lot!

Thanks for all the help.

Best Regards,

Hi Gustavotor,

Sorry, I can't send my code as it belongs to my employer. If you can be more descriptive about what you are trying to accomplish and what issues you are having, I (and I'm sure others) would be happy to try and help.

Thanks,

Amanda