monkeyhead
Member
Hey all, looks like the forum got updated since I was last hanging around here (either that or it's just been a long time.)
Anyway, a little background on my question. We've had this machine that for years has bothered me. Theres a product feeder that has seperate lugs for each order to be processed. A SICK photoelectric prox eye detects (well it tries anyway - prox eyes and clear plastic don't always work so well) the package and tells the machine to feed a carton for the order.
The behaviour that has always driven me crazy is that if the eye flickers at all in it's reading window, the product gets ignored causing problems down stream.
The whole machine is based around an encoder (0-359). In the machine's setup menus, you can adjust the window in which the product sensor will look for the product so the lugs don't get picked up as they pass the sensor.
I finally got hold of GX developer and found the section in the ladder where this is handled. The guy who wrote this used the FSTLP instruction.
Here's a simplified example of what it looks like:
So after reading up on the SFTLP instruction, I'm assuming that it only does the bit shift the first time it scans and M13 is true. This seems bizarre to me, because A. Why even have an adjustable reading window when it only checks it as soon as it opens, and B. This is inconsitent with what I've seen on the machine. I've fought with the stupid photo eye for years. I started out as an operator on this damn machine and I swear that everytime the stupid thing flickers off while product is passing, it won't pull a carton.
So after all that, my very simple question is am I analyzing the FSTLP instruction right?
Anyway, a little background on my question. We've had this machine that for years has bothered me. Theres a product feeder that has seperate lugs for each order to be processed. A SICK photoelectric prox eye detects (well it tries anyway - prox eyes and clear plastic don't always work so well) the package and tells the machine to feed a carton for the order.
The behaviour that has always driven me crazy is that if the eye flickers at all in it's reading window, the product gets ignored causing problems down stream.
The whole machine is based around an encoder (0-359). In the machine's setup menus, you can adjust the window in which the product sensor will look for the product so the lugs don't get picked up as they pass the sensor.
I finally got hold of GX developer and found the section in the ladder where this is handled. The guy who wrote this used the FSTLP instruction.
Here's a simplified example of what it looks like:
M13
---||------------[SFTLP X030 M520 K5 K1]--
M13=Bit that's on during the adjustable reading window
X030=Photo Sensor input
M520=Bit that's set to feed a carton
So after reading up on the SFTLP instruction, I'm assuming that it only does the bit shift the first time it scans and M13 is true. This seems bizarre to me, because A. Why even have an adjustable reading window when it only checks it as soon as it opens, and B. This is inconsitent with what I've seen on the machine. I've fought with the stupid photo eye for years. I started out as an operator on this damn machine and I swear that everytime the stupid thing flickers off while product is passing, it won't pull a carton.
So after all that, my very simple question is am I analyzing the FSTLP instruction right?