how to create alarm based on 2 signals

[rhawk]

I am trying to create an alarm for the following:

After a start signal is sent to a motor i want to have a delay for 3 minutes before i check to if the motor is running. If the run command is still there and there is not run status then i need an alarm

Could i use a one-shot with:

name = verify_motor1_start

on/off signal = start_motor1  (this is the bit that is written to the PLC to start the motor)

timer delay = 3:00

display format = mm:ss

Then create an alarm (logical):

name = confirm_motor1_start

message = "motor 1 did not start"

condition = start_motor1 and verify_motor1_start

If the command to start motor is true and the verify_motor1_start is false then i should get an alarm  -(is this correct)

Would this work?

what kind of problems would i have when the command to stop the motor is sent?

would i have to reset the one-shot if the motor did start and then i stopped it and then later the command was sent to start again?

I hope this makes sense.....

[Mike@DTSI]

Use the Delay-On Timer

condition = not(Motor_Start) and not(Motor_Run)

We typically use :

Motor_Start<>Motor_Run

Good luck
Mike

[rhawk]

Mike,

Thanks for the help. I was not sure how to do this

[Ryan.S]

DeleyOn timer is better.

If the input signal turns on, the timer waits for 5 minutes and turns on. During the 5 minutes, if the input turns off, the timer is reset.

Then, you just need to check whether the motor is running when the timer is on.

But the question is how you determine whether the motor is running? Is there a status register?

[rhawk]

When i want to start a pump, the HMI writes a "1" to a PLC register and the PLC looks at this register to see when to start the pump. When there is a "1" the DO starts the motor. There is a 2 minute delay built into the motor starter, not part of the PLC program, that will not let it start until 2 minutes after the PLC sends the start command. The motor has a contact thats pulls in when the motor is running. I use this contact and bring it to a DI on the PLC. That is how i know it is running and why i need to have a delay before i can do the compare of - did the PLC tell the motor to start and has the motor started after 2-3 minutes.

So i need an alarm generate when the motor start command is "1" and the motor run status is "0" (after the 2-3 minute delay). Status should be a "1" if motor has started.