Keith Menges

MrPLC Member
  • Content count

  • Joined

  • Last visited

Community Reputation

0 Neutral

About Keith Menges

  • Rank
    Keith Menges
  • Birthday 10/02/68

Contact Methods

  • Website URL http://
  • ICQ 0

Profile Information

  • Location Brillion, WI
  • Country United States

Recent Profile Visitors

3601 profile views
  1. Apollo Mission Guidance Computer.....

    That's because cost/benefit analysis says it doesn't have to. The cost of failure in general industry isn't high enough. In my daily job I don't have the lives of three men, the GNP of half the world and the hopes and dreams of a nation riding on my decisions. If I did I would be doing much more true engineering. The cost of failure for these people was extremely high and they didn't have any previous experience to lean on. It was a truly incredible endeavor. I wonder how many people had to bow out because the pressure just got to be too much. Keith
  2. You can look at it one of two ways. In the English system, dividing weight by gravitational acceleration gives you mass in slugs, which is the customary english unit of mass. Or you can divide linear acceleration by gravitational acceleration to give you acceleration in G's. Ultimately you are trying to satisfy the equation: F = m*a and get the units to work out right. Keith
  3. Looks like a pretty reasonable solution. Using the master encoder as a feed forward command value and just using the PID as a trim will definitely help. Be a little careful with the feed forward value. The PID will only allow for positive correction the way it is set up now. If the feed forward value ends up a little too high you have no way to get the slave speed back down. Keith
  4. I guess my question is specific to this situation. Why the flood of messages when you connected the 5/05? It should only speak when spoken to unless it has a slew of Ethernet MSGs in the program. Or do you have an HMI connected to it via Ethernet? Even then they usually don't request that much data. Of any of the AB products you can put on a plantwide network I would think the 5/05 would be one of the safest. Keith
  5. As long as your timing mode is set to periodic the instruction will use the Task period to calculate the integral. So task period times won't affect the integral sum. The easiest way to evaluate what will happen with different gains is to look at what happens to a unit step input. If the integral sum starts at zero, the integrator gain is set to 1 and you make a zero to 1 step input to the instrruction the output of the instruction will be 1 after 1 second. It will be 2 after 2 seconds. Taking the same initial conditions except for setting the gain to 2, the instuction will output 2 after 1 second and 4 after 2 seconds. Notice that the gain is applied to the input prior to summing. This means the gain won't affect the limits, only rate at which the limits are reached. What are you using the instruction for? Keith
  6. Relay Logic Brain Teaser

    You're right, Gerry. I tried to shortcut this with common pushbutton contacts. Each of the latches needs it's own pushbutton contact for this circuit to work. My bad. Keith
  7. Relay Logic Brain Teaser

    That's definetely more robust. As you said it can still get tripped up. But with the extra little bit of hold you have on the reset relay now it would be pretty tough to mess up. Keith
  8. Linear Actuators

    I don't think Peter is advocating using an accumulator instead of a variable displacement pump. I think he is advocating using an accumulator in addition to a variable displacement pump. In that case you could use a smaller pump and motor and allow the pump to refill the accumulator during the dwell time. This would have the dual benefit of providing better response as the pump compensator doesn't neefd to try and react instantaneously to an increase in flow and the idle energy loss will be lower with the smaller pump/motor combination. Keith
  9. Relay Logic Brain Teaser

    speakerman- I'm pretty sure that will work. However, playing the devil's advocate (as I am wont to do) I think you have a possible race condition on the reset latch. If the N/C Reset contact in the Set rung starts to open and drops the Set relay befor the N/O Reset contact in the Reset rung can pull in the Reset coil won't latch. Granted, I'd have to be standing on my head pressing the button with my toe on the fifth Tuesday of the 6th month during a blinding snowstorm for that to happen. Keith
  10. Relay Logic Brain Teaser

    I'm going to have to wire that one up on Monday and try it, panic_mode. That will definitely work in a plc but I'm not sure it will work with hardware relays. It looks like it relies on specific timing to work, which you can't guarantee with relays. Keith
  11. Relay Logic Brain Teaser

    Try this. It takes 4 relays and and two contacts on the PB but it doesn't require a oneshot. Keith Hardware_Toggle.pdf
  12. RSlinx

    That depends on your subnet mask to a certain degree. However, you would be pretty safe with 191.190.191.XXX, where XXX is anything other than 9, 0 or 255, assuming this is an isolated network. If you type 'ipconfig' at the command prompt you will see what your laptop is using for TPC/IP settings. Don't even bother doing anything with RSLinx until you can ping the plc. It would be a waste of time. Keith
  13. PID

    I suggest you read some of the posts here, especially the sections on graphical modelling of the heat exchanger as well as the section about determining gains from the model. I think it will be pretty helpful. However, I don't think the information you have at this point is enough to go on. You will probably need to perform a more structured test. Keith
  14. You need to be a little careful using true torque control, that is providing the drive a torque command. If the web breaks and there is nothing for the motor to pull against the motor will accelerate to very high speeds. You may be better off operating in velocity mode with a torque limit. At the very least monitor the speed feedback and if the feedback is outside of some expected range shut down the drive. How well torque control works on an unwind largely depends on how much of the tension the drive system 'feels'. If you have significant drivetrain torque losses relative to the torque needed for tension torque control becomes very problematic. The torque command is simply: Desired_Tension(lb) * RollRadius(in) / GearRatio / MotorTorqueAt10VDC * BitsAt10VDC You may want to also offset this by the known drivetrain torque losses. Keith
  15. I don't have the information in front of me right now to really look this up, but this might send you in the right direction. As you have seen you have the data bit speed to support what you are trying to do. However, CNet with not allow an unlimited number of connections per NUT. If you have six devices with a 10msec RPI running on a network with a 5msec NUT, CNet need to schedule three connections in a single NUT to get that to go through. That may be where you are getting stuck. Try to set your per module RPI to 6 times your NUT. In your case this would be 30msec. That should be OK. Keith