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Help-me with a new project =)

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I don't have any experience with modbus and my English is very bad


I am trying to make a modbus network, the network will control a lot of vfd's (30 altivar 61 from schneider), its a cold water system with 4 big chillers, they provide cold water for our hvac system.


the hardware is so simple, its PID on v1210 with 7 io-atc8 modules for the sensors, controlling all vfds with this modbus network


i just take some prints and you will see my 2 problems


on the first picture the sb3 is one of the problems, is that correct to take the connections alive? does exists another way to keep the connection alive and keep changing the frequency of my vfds?


on the second picture the problem is bigger, the vfd have a registry that include many bits, its a read registry that show the status of my vfd, but how can i sort out this bits? how can i see the bit's from 3201? i know the 3201 registry have 15 bits, see the picture and you will understand my problem!

picture 3 is the bits of the 3201 registry



sorry for the bad english

Thank you!




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First: if you want to send the message once per sec it is ok. Alternativaely you can use SB13  (is in on at the rising edge on SB3). OR if you have to do it not once a second, you can use a timer. See attached. I use for the keepalive interval about 33% of the timeout of the slave "device".


Second: try the fuction numerics to bits (you can find it in the "vector" menu.). See the help for details.







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thanx a lot man


on the first problem sb13 works fine, but i think the delay that causes could be a problem early... i am thinking about canbus or Ethernet network, just to minimize the delay


on second i just use a numeric to bits, works very well!!


now i can have vfd state, modbus state, acceleration and deceleration time, motor current, and real time frequency, if i want to improve more functions its a simple way...


for now i am doing some stress tests with the pumps, and on next month i want to bring this for my smartphone.

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