08-25-2005 11:04 AM
08-26-2005 12:55 AM
10-08-2008 09:26 PM
1. NI FUBUS - HSE/H1 LD will not work with ControlLogix
2. If you have the latest firmware in your 1757-FFLD(C), it fully supports the 375 HHT.
3. You can use NI FBUS Config with 1757-FFLD, however, NI FBUS Config software does not allow partial downloads (software imposed limitation)... full downloads stop everything on the segment. If you are using RSFieldbus software, you can do partial downloads, add IO (FF Scheduled Communicaitons) on the fly w/o disrupting the network.
4. In theory you can put 31 devices per segment (w/o repeaters), however, this is not practical for various reason (voltage drop, slower updates, VCR connections, and etc.). The biggest thing to watch is the number of VCRs (producer/consumer connections on H1 are called VCRs). A valve could produce Postion, Torque, Alarms, DI and then consume CmdPosition... This valve would produce 6 VCRs and consume 1 VCR. A Temperature probe might only produce one VCR. The general rule is one or two valves and 6 to 8 other devices per segment. If you have two valves (2 x 7 VCRs) and four mass flow meters (4 x 5 VCRs) that means you need to move at least 34 packets (one-way) across the network. FF can only perform 50 messages per second. The bandwith is split between scheduled and unschedule at about 50/50 ratio so you really only get 25 MGS per second scheduled so you are looking at 1.3 seconds of wire time. Realize the device require some time to create this data (D/A) before they can publish the data to the network (not less than 50ms, some times as much as 1000ms). So the real update time could easily be 2 seconds or more (one way across the wire). Given this performance concern, the original FFLD firmware only supported 16 Producer and 16 Consumer connections (VCRs) per segment... Many applications consumed many more data points than they produced (especially application that just monitor data and don't do any loops). So new firmware opens this up to 64 Producer and 64 Consumers per segment..... with a warning that moving this much data across the H1 could be slow.