×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Modbus communication between Alstom Micom Relay and Siemens S7/CP441-2

Modbus communication between Alstom Micom Relay and Siemens S7/CP441-2

Modbus communication between Alstom Micom Relay and Siemens S7/CP441-2

(OP)
Our system configuration is as follows.
a. Siemens S7-400 CPU
b. CP441-2 Modbus master communication module
c. Micom Relay PXX, 24 sets
d. RS-485, Modbus
e. Problem
   - 1:1 communication : No problem
   - 1:N communication : Data missing or mixing(disturbance)

I'd like to know exact cause and solution(with sample program or technical papers).

Thanks

RE: Modbus communication between Alstom Micom Relay and Siemens S7/CP441-2

my understanding is as follow :

with siemens as master and one micom relay, communication is working.

as soon as you plug a second micom, communication fails.

1/ are all micom with differents modbus adresses ?

2/ are RX/TX not crossed ?

are you able to identify one relay raising the trouble ( I mean, if problem is coming fron the second unit, avoid it and jump from 1st to 3rd)

also, be sure that all relay are under modbus and not other protocol.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources