Network Symbols/Net Variables

[BobB 58]

I have not ventured into these things yet. I have normally, with Ethernet IP, just allocated words on the network to each PLC, with great success. I have a job I am programming at the moment, 8 x CJ1M-CPU33, one Ethernet IP connection is through 2 x Adam (Advantech) Ethernet/fibre converters (SC fibre). There is going to be a heap of stuff on the network as I had originally planned to have 3 of these PLCs as remote I/O but the CRM21 masters were in very short supply so had to put in full PLCs. I find that the online help in CX-P re Network Varaibles is pretty brief. From what I can understand so far these things allow acces from other PLCs. Anywhere I can get a decent leaflet/manual or something re Network Symbols/Variables? Any experiences? I am thinking I should probably go the proven way at the moment as I am just starting to wriet the software and we start commissioning early next week. Any advice/help appreciated greatly. I might add that I will probably have to make up my mind about this in the next 12 hours - have to get the job done. Write software really fast but this is a big task in a very short space of time. Have 4 NS screens to do as well. Edited 6 Oct 2011 by BobB

[banker 2]

BobB There is a decribtion on Myomron.com: http://www.myomron.com/index.php?action=kb&article=1321 Hope this help. Banker

[banker 2]

Hi BobB There was a strange limit in the first version of CJ2M plc's, in this versions you was only able to transfere 40 Word in and 40 word out. Banker

[BobB 58]

AARRGHH!!! Too darn fiddly. Back to rolling my own - darn sight easier. Thanks for the responses. Edited 7 Oct 2011 by BobB

[PMCR 66]

Bob The original limit on version 2.0 of the EIP portion of a CJ2M-CPU3x was 40 bytes in / out per connection. That has been removed in version 2.1 of the EIP portion of the CJ2M-CPU3x. The overall limit is 1280 bytes total in and out across all (up to 32) connections. Network Symbols: Making a Symbol a 'Network Symbol' simply puts that Symbol into the Tags Database in the PLC. This makes that data point available by Tag Name across EtherNet/IP to other devices such as an NS. The difference between 'Publication', 'Input", or 'Output' only have to do with how a Network Symbol is imported into the Network Configurator for EtherNet/IP. A Symbol marked as 'Publication' is not imported into the EIP Configurator. A Symbol marked as 'Input' is imported into the Network Configurator as an Input (Consumed) tag,. A Symbol marked as 'Output' is imported into the Network Configurator as an Output (Produced) tag. An NS or other external EIP device can access Publication, Input, or Output Symbols.