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multible Modbus commands in jazz

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The ability to communicate with multiple decies can be done in several ways, but one was is like the picture (I hope) from the gallery.

modbus serial Com Net

Use an array method where each read/write line is executed based on if a memory integer equals a particular value. At the end of each net increment the integer by one and after you have gone through all of the read/write lines you want implemented then reset the memory integer to zero so the process can start over again. You have decisions to make on what to do when communication fails for one or more of your devices, but I do not have the time to gothrough all of that here. There was another forum question just earlier this week on that subject and some discussion was made in that line.


Yay the picture got put in !!! Thank You Cara :D

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  • MVP 2023

The nets in the picture are probably banging the serial port too quickly and not allowing the Modbus blocks to finish before incrementing to the next block. I'd slow it down a bit with a separate net monitoring the value of the Modbus status register value and a short timer in front of the INC block before proceeding on to the next address.

As Keith said - You'll have to make some decisions as to what to do when communication fails. The picture he posted is a starting point and will need to be modified to handle errors.

Joe T.

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I use have this method to talk to 8 devices simultaneously with 3 reads and two writes each for a total 40 reads and writes and it works well. Post your program and lets see if we can figure out what is going on. I have never uses a Jazz to do communications, I find the Jazz way too limiting.

I generally would not use anything less than the V130 when I am doing Modbus comminications personaly. The cost of the Base V130 is not different enough from the cost of a Jazz combined with the required port hardware to make the communication possible.


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