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noxcuses

TCP/IP vs CIP Connections

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I'm considering using the new CompactLogix packaged controller (L23E) on a project instead of a L32E. I was reading the referance manual and noticed that the L23E ethernet port is not the same as a L32/L35E. It can only do 8 TCP/IP connections and 32 CIP vs the 32TCP/IP and 32 CIP connections of the L32/35E. Also the transfer rate is 2000 packets per sec vs 4000 pps of the L32E. Wouldn't this limit the L23E to only 8 device connections over ethernet? I know the processors counts a connection between any I/O and the processor as a CIP connection, but doesn't it also count as a TCP/IP connection? I have always thought that any connection over Enet would be counted as a TCP/IP connection and CIP connections were counted over Enet, backplane, and other media. I'm I thinking correctly here or totally off base? For example, A L23E connected to a 1734-AENT would use 1 CIP and 1 TCP/IP connection. I'm thinking that would only apply when using Unicast Connection. Edited by noxcuses

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Both CIP and TCP/IP are "connection oriented" protocols and because CIP uses TCP/IP to do much of its work the terminology can get confusing. For purposes of network estimation think of TCP/IP connections as equal to the number of connected devices with Ethernet plugs. Multiple CIP Connections can run over a single TCP/IP connection. Consider a 1734-AENT equipped with a handful of discrete modules configured as a Rack Optimized connection plus two Analog Input modules. The TCP/IP connection to that 1734-AENT will be used to configure and service three CIP Connections; the Rack Optimized Connection and two Module Connections. Another example is a PanelView Plus operator interface. It makes one TCP/IP connection to the controller and then runs CIP connections for the data provider, the trending system, the alarm system, and the global objects system. It can make up to five CIP connections to the controller. There are some good Knowledgebase documents on this topic and the Ethernet Devices in Logix 5000 Control Systems user manual (ENET-UM001) is an excellent resource too.

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Thank you for the info! I was hoping to use the L23, but with 7 devices on the network it's a little too close for comfort.

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