There is sth wrong when connecting PV Plus to CLX

Before, we used a switch to connect the PV plus and the CLX through a ENB module. Now, we want to leave the switch out, and use a cable to connect the PV plus and the CLX directly.
But it seems that the communication between the two failed. And when we added the switch, they worked well then.
Please help me, how can I solve this prolem?
Thanks very much.

Did you try a cross over cable?

Crossover cable is not necessary. I have one sitting 2 feet from me connected directly to the PLC with a straight through cable.

edit: I guess I don't know what model of ethernet card is in your rack, so if it's old enough, you may need a crossover cable. Take Bob's advice!

I would personally try using a crossover cable first. Most newer equipment will figure out if the cable is a crossover or not and adjust accordingly. dmroeder says the ones he is using doesn't need it, but maybe that was added in later revisions of the hardware? I have no idea, but a crossover cable is very inexpensive and worth a try. I would also double check your IP address settings on both devices and make sure that they are on the same subnet (192.168.1.xxx for example) and have the same netmask (255.255.255.0 for example).

A switch really doesn't add anything to the equation other than crossing over RX and TX, unless there is more than just the 2 pieces of hardware on the switch.

Some laptops have auto switching. I have used straight cables for all purpose on my laptop but older laptops dont support them i guess

Thanks, Bob and all.
The problem has been solved.

You are welcome..But what was the solution for future readers?

I just used a cross over cable, and it works.

Glad you got it fixed. Figured that was about all it could be.