"Daisy-chaining" Managed Switches

[BillRobinson]

Just wondering if this is a no-no.

Just as a background i'm using Allen-Bradley RSLogix 5000 over Ethernet/IP with remote IO racks and 3rd Party HMI. The switch is a Hirchmann with IGMP snooping enabled

I was doing an upgrade to an existing site last year which required an extra Ethernet connection to the thier PLC network. The existing switch had already used up all of it's ports so instead of replacing the existing switch I added a smaller switch and "jumped" the 2 switches together with a normal ethernet cable.

I was later told by a network guy that this is a bad idea.
Any thoughts?

 

[1_1_1]

well you want to keep an eye on the number of switches

the max number of switch hops is 4

so is you branch off of the MDF switch to the Hirchmann then just don't go to 4 Hirchmann but you might not be connecting to a plant wide network so then you can use 4 Hirchmann but don't make a loop

and it is better to use a larger switch than a bunch of switches but PLC's won't see the benefit

if it is a plant wide network then you'll want to watch how many switches have to go through for one thing to reach another