Good Morning,
I am troubleshooting a Devicenet issue for a customer. The Devicenet network is having dropout issues, mostly in the morning. It has 24 slave.
One issue is that there was a slave that was removed from the network, but had not been removed from the scan list. I removed the slave, but dont think it would cause dropout issues.
I verified that a 120 ohm resistor is on each end of the network, and I even replaced them with new resistors.
Another issue that I thought may have played a part was the L55 processor was running version 15.5 firmware and the 1756-DNB was running version 12.003. I found a 1756-DNB with version 6.002 and replaced it.
Some of the other issues I found was that it appears that the Devicenet cable is not using the shield and is not grounded.
Another issue is that the power for the devicenet is the same 24vdc power that is used for all of the IO. I read in the troubleshooting guide that you should not use the same power for devicenet as IO. How do you normally handle powering the devicenet if you have a battery bank with a charger and need battery backup?
I checked all of the connections and they seem secure. I checked voltages on the Can-L and Can-H and they seem correct. Impedance on the bus is right t 59 ohms so that is good.
I dont have a scope, so I cant tell if there is any noise, but I would think it is a good possibility due to no shield in place.
I think some of these issues may play a part, but this place has been in service for a long time and this issue just recently popped up.
Anyone have any ideas or feedback?
I am troubleshooting a Devicenet issue for a customer. The Devicenet network is having dropout issues, mostly in the morning. It has 24 slave.
One issue is that there was a slave that was removed from the network, but had not been removed from the scan list. I removed the slave, but dont think it would cause dropout issues.
I verified that a 120 ohm resistor is on each end of the network, and I even replaced them with new resistors.
Another issue that I thought may have played a part was the L55 processor was running version 15.5 firmware and the 1756-DNB was running version 12.003. I found a 1756-DNB with version 6.002 and replaced it.
Some of the other issues I found was that it appears that the Devicenet cable is not using the shield and is not grounded.
Another issue is that the power for the devicenet is the same 24vdc power that is used for all of the IO. I read in the troubleshooting guide that you should not use the same power for devicenet as IO. How do you normally handle powering the devicenet if you have a battery bank with a charger and need battery backup?
I checked all of the connections and they seem secure. I checked voltages on the Can-L and Can-H and they seem correct. Impedance on the bus is right t 59 ohms so that is good.
I dont have a scope, so I cant tell if there is any noise, but I would think it is a good possibility due to no shield in place.
I think some of these issues may play a part, but this place has been in service for a long time and this issue just recently popped up.
Anyone have any ideas or feedback?