DeviceNet and SMC EX250-SDN

[mailpikacom]

Can anyone help me with the following problem:

I'm using SMC pneumatic module EX250-SDN on a DeviceNet with Allan Bradly DeviceNet Scanner 1747 SDN. And every time I disconect power supply for valves this EX250 module reports (minor) error to Scanner and this makes Scanner go to fault mode. And when I reconect powers supply for valves it takes up to 12 seconds befor Scanner Module goes back to normal operation (starts communicating with E250). Any possibilities to make this reestablishment of communication faster?

 

[VEBill]

You would have to check with the OEM (their engineering support folks). They'll probably recommend a UPS for critical applications. It's likely that nothing can be done, but you should check with them to make sure.


Commentary: Such delays seem common in many modern systems. My dad's first TV changed channels in a fraction of a second; modern digital TV systems take several seconds to lock-in to each channel. One used to be able to set a watch by the BBC time signal on old fashioned shortwave; now the beeps arrive about 18 seconds late via XM satellite radio. Sigh... ;-)

 

[controlsdude]

I believe you should get a fault back from the node but the device should not make the scanner card go into fault. Their is probably something not configured correctly or a bad eds file. Is the EDS file for the valve correct? Did you check for product problems on the ab site on the devicenet card? Is their known issues from the manufacturer on this valve? Resistor Terminations on both ends correct? When you have the network powered down and disconnect one end of the termination do you see that resistance from the other end? (120 ohms i believe)

Did you check the diagnostics on the node for any faults?
You can get a devicenet checker device from a local ab rep to check the integrety of your system. If the valve is putting out something bad on the network it would find it.