The Waterboy
Member
- Join Date
- Jun 2003
- Posts
- 12
I've looked through the archives and can't find anything that has worked, so here's a call for help:
I've got an overhead crane with a wireless connection to a ground-based HMI. On the crane is the wireless client (a D-Link cheapie), a 5-port Cisco managed switch with IGMP snooping enabled, a Panelmate, and the Control Logix rack with 1756-ENBT card.
The PLC only answers pings from the ground about 25% of the time. You get about 2-3 minutes of connectivity, followed by 10 minutes of nothing. Lather, rinse, repeat all day long.
The initial suspicion is the wireless client, but I can get online (via HTTP) with the wireless client and the Cisco switch 100% of the time, and I can ping the Panelmate 100% of the time with 1-3ms times. All of this is from the ground HMI.
What is most odd is that I can do the ping xxxx -t thing to the PLC from several PCs at once, and they all lose connectivity at the exact same moment. While I do that, I also ping the wireless unit to be sure I'm not losing it, and it never blinks.
No fault codes or errors are showing on the ENBT. I'm stuck. I'm also predominantly a Siemens guy so my Control Logix skills are only at a basic 'get online and look at properties' level. I've replaced the cable from the PLC to the switch, as well as the switch itself, to no effect. Can anyone suggest a course of action?
I've got an overhead crane with a wireless connection to a ground-based HMI. On the crane is the wireless client (a D-Link cheapie), a 5-port Cisco managed switch with IGMP snooping enabled, a Panelmate, and the Control Logix rack with 1756-ENBT card.
The PLC only answers pings from the ground about 25% of the time. You get about 2-3 minutes of connectivity, followed by 10 minutes of nothing. Lather, rinse, repeat all day long.
The initial suspicion is the wireless client, but I can get online (via HTTP) with the wireless client and the Cisco switch 100% of the time, and I can ping the Panelmate 100% of the time with 1-3ms times. All of this is from the ground HMI.
What is most odd is that I can do the ping xxxx -t thing to the PLC from several PCs at once, and they all lose connectivity at the exact same moment. While I do that, I also ping the wireless unit to be sure I'm not losing it, and it never blinks.
No fault codes or errors are showing on the ENBT. I'm stuck. I'm also predominantly a Siemens guy so my Control Logix skills are only at a basic 'get online and look at properties' level. I've replaced the cable from the PLC to the switch, as well as the switch itself, to no effect. Can anyone suggest a course of action?
