When designing or upgrading a system which relies on a network, bandwidth is always a concern.
Rockwell's Ethernet/IP Capacity Tool, which can be freely downloaded here or here, allows the user to select a platform, add different types of I/O and network devices, and then calculates how many CIP and TCP connections are consumed along with the packets per second (PPS) needed to service the network.
Below I'll walk you step by step through using this tool to calculate the connections and PPS requirements of a sample system:
Step 4: Now in the top left drop-down (above the “Node Group 1” box) we'll select “Point I/O Rack” as shown below:
Step 5: Change the “No. Racks” for the Point I/O to 4:
Step 7: With the four Point I/O racks added, press the “Compute” button found half way down on the left side of the program. This returns the number of connections and PPS used, as well as how many are remaining. Since we are still within our limits all the results are green:
Step 8: Let's add some VFD's to our system. Select the dropdown above “Node Group 2” and choose “PowerFlex 525 Drive” from the list:
Step 9: Now, look under the picture of the drive you have just added – you have a field to enter the number of drives (on the left) and the update rate (on the right.) In the left hand box under the drive's picture change the number of drives to 4 as shown. Note: Sometimes the text doesn't display in the correct location, as is the case below. Hey, it's free right?
Step 10: Press the “Compute” button. The software reports back that we have exceeded the limit of 8 Ethernet/IP I/O drops for the L24. However, we only have 8?
Note: This does not mean you can't have an IGMP switch in this system, it only means that if the switch was added to the RSLogix5000 I/O Tree it would consume one of the L24's eight Ethernet I/O racks. In our example, we won't be adding the switch to the I/O Tree (in order to allow our L24 to have 4 racks of Point I/O and 4 PF525 drives.)
Step 13: Next we'll add some HMI's. In the “Node Group 3” section,n select the PanelView Plus from the dropdown, read the popup and press “OK:”
Step 15: As you can see below, event though our L24 has no more room for Ethernet/IP I/O, it still has plenty of bandwidth for HMI's. In fact, this is a key feature of the entire line of 5370 CompactLogix controllers.
Step 16: To see how the older line of CompactLogix controllers were much more limited when it came to the number of HMI's that could be connected, lets change the L24 to an L35E (as shown below:)
Step 18:To find a working number of HMI's for this system, reduce the number of PanelView Plus units down until you can press “Compute” and not have a red result for CIP connections. In my test below I maxed out at three PVPlus units.
I hope the above step by step walk-through of using the Ethernet/IP Capacity Tool is helpful. If you have any comments or questions on this tool please feel free to leave using the “post a comment or question” link below.
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