Siemens S7 300 vs. ET 200S for remote I/O

Just curious about the pros and cons of using "full blown" S7-300 racks & I/O with profibus or profinet comm modules vs using a similiar ET-200S "rack" with the same amount of I/O. If each "rack" (s7-300 vs et-200s) contained the equivalent of 12 ea. 16 point discrete Input and Output cards, would there be an appreciable difference in speed or performance?

I would appreciate any information on the tradeoffs between speed, cost, cabinet space, installation, troubleshooting or any other issues people have found.

Thanks

Hello Sam.

ET200S is our favourite i/o hardware.
We even use it where we could have used S7-300 i/o directly attached to the CPU.

There is a FAQ about calculating the update rate of i/o on Profibus, and with ET200S in particular. I havent compared ET200M and ET200S, but I expect the update rate to be almost identical.

ET200S will be wider than ET200M, but to my opinion the easy access from the front is better with ET200S. In many cases you can omit a separete terminal strip. ET200S modules with 8 24V inputs or outputs have just been released. They can reduce the width to comparable to ET200M. I havent tried them (yet).

ET200S is slightly less expensive than ET200M.

Troublshooting is similar as with ET200M or S7-300 i/o. STEP7 Hardware diagnostics is essential.
I am about to implement the socalled "Report System Error" so that my HMI will have just as good HW diagnostics as STEP7.

I once met an irishman in a bar in egypt, and we came to talk about ET200S. He was not happy with it, but he didnt elaborate.

I am using an IM151-7 and ET200S modules as a cheaper alternative to a S7-300.

When I first started this job I wanted to start using Automation Direct Terminator I/O. When I put pen to paper the ET200S was cheaper than AD. I have had no problems with the ET200S at all. I have not used any S7-300 so I can't help with that.

S7-300 IO in a remote rack is called ET200M. The big advantage ET200M has over 200S is the number of IO points per module, and the number of available modules to choose from. The ET200S is a better choose if your application calls for smaller IO counts per drop. ET200S is the only one today that has a interface module for PROFINET, and ET200S offers better options for Failsafe applications. ET200S also allows removal and insertion under power capability, the ET200M requires a active backplane for this.

I personally prefer the ET200S unless the application calls for a higher number of IO points per card. My reasons, 1) Easier to wire, terminal block included, 2) PROFINET today, 3) Failsafe option is better, 4) RIUP standard, 5) Lower cost IO modules, 6) Motor Starter and Drive options are available, 7) Faster backplane, 8) Optional CPU (IM151-7)

For new installations I recommend PROFINET and the new IM151-3 HF with built in 2 port switch. It allows a larger number of IO modules per drop, and allows a typical line configuration to be used instead of a star topology you see with most Ethernet installations.

JesperMP,
Do you know the path to the FAQ for the profibus update rates.

Thanks for all the comments. We're trying to decide if a "standard" Controllogix configuration with 16 I/O slots would work best converted to S7300 or 200S. I misstated my first post so it sounded like I was asking for 32 slots.

This is an easy to use one:
http://www.automation.siemens.com/perfdata/DPRea/DPRea.aspx?lang=e


There was also a more manual calculation FAQ but I cannot locate it at the moment.