×
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

motor sequencing - ladder logic required

motor sequencing - ladder logic required

motor sequencing - ladder logic required

(OP)
Im new to plc's and need some help on efficient motor sequence ladder logic:

Inputs(control) - motor  1
                  motor  2
                  motor  3
                  motor  4

Outputs -         motor  on 1
                  motor  on 2
                  motor  on 3
                  motor  on 4

If only one motor is trying to start (one input high) then it should start instantly and then block the other motors from starting for a time period.
If two or more are trying to start together then one with higher priority should start instantly then the other(s) after the time delay and so on.

Can someone please provide the ladder logic for this design with description of operation.

Thankyou for any responses :)
Sean

RE: motor sequencing - ladder logic required

Dear Lanky,

From the posting, I assume that finally all the motors will  get started sequentially after a prescribed time delay. Correct me If I am wrong.

Also how is the priority defined.

If it is a contact, priority can be ANDed with the Input to run one motor. Make such that when this motor starts, it initiates (starts)a time delay, say T1 for motor 1. If motor 2 is going to start, let that be T2. This  TIMER T1 ON(RUN) contact can be used to disable the outputs of other motors 2,3,4.

again the priority contact / bit will enable the start of the next "suited" motor. Here another Timer T2, T3 T4 will start and will block the other pumps. A symbolic rep is given down:
(Sorry Lanky, I couldnot post the rungs. Your e-mail will be useful)

P1 is the priority Bit/ contact for Motor 1 (O/P 1)
If any other timers are running it will not allow the motor 1 to start.
If motor 1 got enabled thro this logic and starts, then T1_R in other logics
will be  “1” and will not allow  other pumps to run till 40 seconds  delay
of T1,  even if its priority bit is set.


Similarly  for motor 2 (O/P 2)
I/P 2        P2           T1_R     T3_R     T4_R               O/P 2

Everything can be put in AND ed logic.

K.G.Vijaya Kumar

RE: motor sequencing - ladder logic required

Just to elaborate on kgvijayakumar's statements a little more.  With regards to ladder logic, and AND function is a line with all of the required inputs that are to be ANDed together with the output being the desired output coil to be activated.

---||------||-------||---------------------------( )-
Input1   Input2   Input3                       Output

Input1 & Input2 & Input3 = Output

Good Luck and keep us posted!

RE: motor sequencing - ladder logic required

A more "elegant" solution would be to use a compare function with a timer (for timing purposes)and a move statement (for the priority)...a little more programming experience would be required.  The logic is a lot less cluttered.
Good luck!!

RE: motor sequencing - ladder logic required

there is a conveyor belt on which  there r cages.there r in all six motor,s(induction motor)i.e these motors r running the conveyor belt. conveyor belt is divided into subloops according to the motors[speed], now when cage goes from one sub loop to another pushers r used also proximity sensors r used ,I want a ladder logic for synchronization of all subloops.

RE: motor sequencing - ladder logic required

Without Knowing your plc best I can do.

-| |-  N.O.
-|/|-  N.C.
-|^|-  Trans On or One shot
-(S)    Set
-(R)    Reset
-(TMR)  Timer




     Start1   Hold   stop1       Motor1
-----| |-----|/|-----|/|--------( )
                     |
                     |
    Motor1       |
-----| |-----------

      Motor1        Hold
-----|^|--------(S)


     Start2   Hold   stop2       Motor2
-----| |-----|/|-----|/|--------( )
                     |
                     |
    Motor2       |
-----| |-----------

      Motor2        Hold
-----|^|--------(S)


     Start3   Hold   stop3       Motor3
-----| |-----|/|-----|/|--------( )
                     |
                     |
    Motor3       |
-----| |-----------

      Motor3        Hold
-----|^|--------(S)


     Start4   Hold   stop4       Motor4
-----| |-----|/|-----|/|--------( )
                     |
                     |
    Motor4       |
-----| |-----------

      Motor4        Hold
-----|^|--------(S)


      Hold
-----| |---------(TMR1)

      TMR1         Hold
-----| |----------(R)

RE: motor sequencing - ladder logic required

A neat way to do this would be to have a motor start event to trigger a start inhibit that precludes further starting for desired period. Since scan time is probably 8-10ms; it's unlikely that multiple start buttons can appear simultaneously pressed, which, according to Einstein, simultanity can never be demostrated; but, I digress. We can post a solution here; but, that would spoil your fun. The above suggestions are perfectly acceptable

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