Mark The Spark

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About Mark The Spark

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  • Location New Forest, UK
  • Country England
  • Interests Steam & necrotecture!
  1. tough connectors

    one of those 'doh' moments? I'm using Lapp cable and love the stuff - did'nt even know they did connectors? - will have a look at harting again too - not used them in ages - used to use their 200 odd pin connectors, and those horrible varelco things.
  2. tough connectors

    I've an odd application where I need some decent connectors: They must be:- Field wireable by frozen fingers 6 pole / pins (or more - but I need 6) have a reasonably decent shroud / cover (but not waterproof - splash maybe). have a PCB mounted mating other half - male or female dont matter - pref 3.5mm pitch. have a good latching action or jack screws volts and current - 24Vdc 200ma - peanuts! Not be a 'D' type - I hate them! - I want something bigger. Anyone used anything they might recomend?- I've trawled Phoenix and Weid to no avail.
  3. Vertical/horizontal DIN mount

    'Top hat' Din rail or 'G' type? Anywhos - I've been known to drill holes in them and mount 'cross rails' on standoff's - mounting the cross rails on a few inches of m6 threaded stud with double nuts. In fact with a bit of doubling up you can make a strong enough 'stand' to take a door interlocking isolator. If you cant drill them? a lightweight device could be mounted off some earth terminals?
  4. OT But Urgently Need Help

    As with any machine - check the level of protection required by the light curtain / drive interlock is correct to suit the application. In many instances because the curtain is being interrupted frequently and the safety system 'checked' each time just a 'Run hold' MAY suffice. This could be further interlocked by a movement detector that pulls the drive power if for some reason the curtain system fails. Also - if a frequent drive interruption is required due to the dangers involved then use a drive that's circuitry does comply with the relevant safety standards in that region. Or - fit a clutch / brake system - again that meets relevant standards, I like a drive that complies AND a clutch! - (cos it might be my paws wot get squished!). EN 954-1, Machine directive etc all give good pointers as to how to design a reliable safety system - but at the end of the day it must be workable else someone will disable it to make working the machine easier! I'm a tad long in the tooth - used to always fit monitored loop contactors to DC drives etc and did not like the early 3 phase drives because a lot of 'em did not like having open output circuits - hence I have fitted a few clutches or supplementary 'movement / kill' devices to machines where the risks were great. As for drives with 'built in' safety circuits - well if it's got a micro doing it would you put your head under it? Saw a chap demonstrate a laser light guard the other day by putting his hand where it would be crushed if the device failed - brave? - nope foolhardy and stupid I'd say, ALWAYS use a test rod / sacrificial part when testing safety circuits, they are not guaranteed NOT to fail - just not LIKELY to fail unsafe.
  5. Function Block for Software Cam shows the fun I had setting up compare tables. look at the last bit of code to see how it finaly worked. You should be able to connect your encoder to a high speed counter and then manipulate the positions you require and stick the positions into a compare table. The tables then fire off interupts where you can set flags that call timers up or just use another position to turn off your 'cam in position' flags. In effect with a bit of data crunching you have a limitless 'soft cam' available (as once a position has been passed you can recrunch and set new targets).
  6. shaker

    Must admit I would go with 2x timer relays (delay on and off) using their N/C outputs in series in a 'all hold' or stop feed line. Poss use mercury 'tilt' switches in this app? if prox or optical give problems? I've seen presses wrecked by lube monitors which only looked for the sensor to be on for 'good' (they were using only a delay off timer and if the sensor stayed on the timer never timed) therefore I always trap for a stuck ON sensor as well as a stuck off condition. As for shakers - anyone else have probs with the modern electrical ones? they dont seem to last anywhere near as long as the old ones (and I do check the current etc) - I've given up using electrical ones in powder plants etc and use the air type - dead simple and very reliable.
  7. PWM CJ1M

    After more tests I'm now pretty sure that PWM commands do not work at all in anything other than the main cyclic programs - although an INI that turns them off does? If anyone knows otherwise please tell me how......
  8. PWM CJ1M

    I've tried putting my PWM 'on' signal into an interupt task (255) which is called by a TKON instruction - no joy, no output at all now. I've also got P_ER flags on my PWM commands in my interupts (which I know are being called as I have activity flags) and they DO NOT come on even if I call the first @PWM from a cyclic task. Methinks the big book may be wrong as it states that PWM commands can be within all types of program area - it would appear that within an interupt task they are ignoored? Anyone know a way round this? I need a very quick change in the PWM duty factor when anyone of 10 interupt tasks are called.
  9. 3g3rv-p10st8 Communication problem

    Aha!, anyways- the magnetic contactors twixt the inverter and motor would be my first port of call. After all the drive should be well shielded against itself and as long as he's kept the cables apart and it's grounded correctly should not be the source of the noise. I used to always have 'loop contactors' on drives and they can give no end of problems if they do not come in before the 'enable' signal is on (therefore giving a good splat as they make contact) and also can be tricky to 'snub' the coils of as they can be big beasties and give ugly back EMF's. And if you cant get rid of the noise then fibre is the way to go with the serial link if it's likely the 'entry' point is not at one end - used to do loads of DNC links to plasma cutters and the like - fibre was the most reliable connection in that very noisey enviroment.
  10. 3g3rv-p10st8 Communication problem

    Is it the 'magnetic contactors' that are coming on at startup giving you the 'splat' of noise?? could well be just the coils on these that need a snubber? As previous keep the 'big stuff' away from the little stuff. You may need to use fibre if the RS485 is getting hit on the way to the screen but I expect its coming from a 'common source' - may be the power to the PLC needs to be hooked up via a UPS to keep it away from the inverter power if its 22Kw and has no 'reactor - filter' (which it ought to have). Also could you not set the inverter output to a very soft start to reduce any noise fro the motor / drive.
  11. PWM CJ1M

    How many times did I read that section & not see that!!! Well I only call my PWM ins with @ so it should'nt be getting more calls but I'll set some traps to check... Seems odd to have a In/Out of an interupt task instruction error? I set my motion off in the main cyclic program and wish to change the duty factor to slow down the motor from interupt tasks, looks like I may have to call all my PWM commands from interupt tasks?? And I'll have a hoover up of any other pulse commands that may still be lying about in my cyclic (I was playing with frequency stuff earlier). Thanks all.
  12. PWM CJ1M

    Anyone know of any restrictions to using the PWM command? Im running some 'direct' servo motors (PWM - DIR control) where I set the PWM duty cycle to alter the speed (frequency is constant), I've got some interupts called by prox sensors and positions and wish to slow down the motor by shoving in a new PWM duty cycle (I rerun the PWM command after changing my duty ratio value). I found that if the PWM command is within an interupt nothing changes, if I set a flag and use the main program to change the PWM it works!? This is not mentioned in any manual I can find, it also makes it rather slow to change the speed of a servo motor, anyone know any facts on PWM? also does the same limitation occur when using a proper 'motion control' module instead of the CPU22 I have? And 'Morgen' to those folks in 'den Bosch' Tashinz visited the other week....
  13. CX-Designer improvement requests

    <file> <print> <image file> <image file output details> jpg or bmp, will print all screens at once or one screen only to files named: Screen0001.jpg etc, to wherever you want them stored. But you get garbage for numbers which are 'real' and still need to cut and paste these with decent values to use in manuals.
  14. CX-Designer improvement requests

    When in test you can 'print screen' to grab the image or 'print to image' in 'print' menu does jpgs but with garbage for numbers. But I use MWSNAP a utility that allows you to select the screen area and add cursers.

    Although you can just use the internal pull ups to the inputs to make the NPN encoder drive the PNP inputs on the PLC I would use 3 opto couplers to separate the Encoder from the PLC and provide the 'inverter/buffer' you need. These and other similar 'buffer/optocoupler' terminals from wiedmuller etc would allow you to hook up the Encoder with little effort and no risk of killing it! In the case of the Entrelec/Abb terminal shown: connect Encoder output A to terminal A1, connect term A2 to your +V supply to the encoder (these can be inverted with no problems!), connect output buffer term + to your PLC Inputs +V Common rail and connect the - output of the buffer term to your PLC's digital input terminal for Enc A (IN04). Do the same for EncB(IN05) & Z(IN06). These are the connections for the HSC, You would be best off using one of the 'high speed' counter' channels as they have the quadrature and filter functions in the PLC setup pages - you can select what rate to set the counter at and if you want 4x pulses going in the counter. If the pulses are mega slow you could just hook them to a standard high speed input and call an interupt that increments your counter - but without using a HSC you always run the risk of losing a few pulses - you might think the pulses are slow but what happens if the machine is stopped with the encoder just on/off a line 'jittering', without using 4x quadrature and HSC your low speed counter would clock up 'phantom pulses' that the HSC would filter or count up/down correctly. This is a 'belt and braces' system, the LEDs on the isolator terminal shows you the encoder is working, you could have different voltages on the Encoder and PLC (maybe have to use slightly different buffer term), you run no risk of killing the encoder output as it only drives an LED that has the proper pull up / down value, the input to the PLC is buffered giving the PLC protection from the nasties in the outside world. And it looks neater than resistors soldered all over the place. I use these for many Encoder / Sensor inputs and use the 1&2Amp versions on Valve outputs from the PLC.