Does anybody have any experience with doing Profibus over a wireless system?
We have a concrete plant about 11 years old that has a kiln car which places the blocks in any one of 14 bays. Each bay is approximately 100 foot deep. While running into these bays, there is a multiwire cable on a spool that uncoils as it goes in and coils back up as it comes back out of the bay.
We are having problems with our Profibus network. The PLC is a Siemens S7 318-2. From our DP Master card, the Profibus runs out to a control cabinet on the kiln car that travels with the car side to side as it goes from bay to bay. In that cabinet, it goes to some remote I/O and 3 SEW drives. We generally have no problem communicating to that cabinet. This one never goes into the bays but just goes side to side.
Here’s where it gets hairy. The Profibus has to go to another cabinet that travels in and out of the bays with the car. This cabinet contains another set of I/O and 2 more SEW drives. The OEM ran the Profibus on this cable along with the 480 that goes to the drives in the second cabinet.
In order to overcome the interference generated by the 480, there are a pair of devices made by Wampfler that take the Profibus signal on one end, amplify it and then convert it back as it goes into the second cabinet.
Our problem is the Wampfler device is no longer made and we cannot find one to save our lives. We have had two die in the last month (due to an underlying cabling problem that we have since found and fixed). The bottom line is we blew out one that was working and our only spare. We planned to re-do the controls on this cabinet in February so I’m just trying to get it going until then (We’re no where near ready to do the rebuild now). The Wampler is more than just a simple amplifier; they work in pairs with the second device acting to reconvert the signal back into the Profibus. The signal is actually carried on a 240 V system between the Wampflers.
We are certain that the Wampfler is the problem because we have full communication if we run a properly shielded Profibus cable between the two cabinets directly. Unfortunately, it will be a fair bit of fabrication to rig something up to handle the cable as it goes in and out of each bay and frankly, we might not have room for that anyway.
We are in the process of trying a pair of devices made by Phoenix Contact (PSI-WL-S232-RS485/BT) to try to send the signal over wireless. We worked with the Phoenix Contact tech support and we briefly got it working after changing a few setting on our HW Config for that network. Under Properties-DP Master system, the Phoenix Contact support had us change the number of repeaters to a really high number (I’m blanking right now and I’m not on line with it) and change the cable length to 9999 km (equator to North Pole).
At this point the system briefly worked. We’re not sure why it stopped working. More accurately, we’re not sure why it worked in the first place. If anyone has had better success with another wireless solution, I’d love to hear it.
I'm wondering if there's something in the PLC code that is sensing a different timiing on the Profibus now and registering it as an error and shutting us down. Unfortunately, I'm much more comfortable in the AB world and most of the error functions are written in STL (where I'm a complete neophyte). I'm workign with the OEM tio try to figure that out, however, we’re reaching desperation since the OEM is in Germany and shuts for two weeks starting tomorrow for the Christmas holidays.
Merry Christmas.
We have a concrete plant about 11 years old that has a kiln car which places the blocks in any one of 14 bays. Each bay is approximately 100 foot deep. While running into these bays, there is a multiwire cable on a spool that uncoils as it goes in and coils back up as it comes back out of the bay.
We are having problems with our Profibus network. The PLC is a Siemens S7 318-2. From our DP Master card, the Profibus runs out to a control cabinet on the kiln car that travels with the car side to side as it goes from bay to bay. In that cabinet, it goes to some remote I/O and 3 SEW drives. We generally have no problem communicating to that cabinet. This one never goes into the bays but just goes side to side.
Here’s where it gets hairy. The Profibus has to go to another cabinet that travels in and out of the bays with the car. This cabinet contains another set of I/O and 2 more SEW drives. The OEM ran the Profibus on this cable along with the 480 that goes to the drives in the second cabinet.
In order to overcome the interference generated by the 480, there are a pair of devices made by Wampfler that take the Profibus signal on one end, amplify it and then convert it back as it goes into the second cabinet.
Our problem is the Wampfler device is no longer made and we cannot find one to save our lives. We have had two die in the last month (due to an underlying cabling problem that we have since found and fixed). The bottom line is we blew out one that was working and our only spare. We planned to re-do the controls on this cabinet in February so I’m just trying to get it going until then (We’re no where near ready to do the rebuild now). The Wampler is more than just a simple amplifier; they work in pairs with the second device acting to reconvert the signal back into the Profibus. The signal is actually carried on a 240 V system between the Wampflers.
We are certain that the Wampfler is the problem because we have full communication if we run a properly shielded Profibus cable between the two cabinets directly. Unfortunately, it will be a fair bit of fabrication to rig something up to handle the cable as it goes in and out of each bay and frankly, we might not have room for that anyway.
We are in the process of trying a pair of devices made by Phoenix Contact (PSI-WL-S232-RS485/BT) to try to send the signal over wireless. We worked with the Phoenix Contact tech support and we briefly got it working after changing a few setting on our HW Config for that network. Under Properties-DP Master system, the Phoenix Contact support had us change the number of repeaters to a really high number (I’m blanking right now and I’m not on line with it) and change the cable length to 9999 km (equator to North Pole).
At this point the system briefly worked. We’re not sure why it stopped working. More accurately, we’re not sure why it worked in the first place. If anyone has had better success with another wireless solution, I’d love to hear it.
I'm wondering if there's something in the PLC code that is sensing a different timiing on the Profibus now and registering it as an error and shutting us down. Unfortunately, I'm much more comfortable in the AB world and most of the error functions are written in STL (where I'm a complete neophyte). I'm workign with the OEM tio try to figure that out, however, we’re reaching desperation since the OEM is in Germany and shuts for two weeks starting tomorrow for the Christmas holidays.
Merry Christmas.
