Ethernet I/O Master vs ERM

[lyndonschroeder]

I am using a DoMore H2-DM1E and I have a second slave base with an EBC100. Can you enlighten me as to when I would want to use an ERM100 instead of using the Ethernet I/O Master?
 

[BobO]

Do-more's Ethernet I/O master provides a higher level of integration than is currently supported by the ERM100. Unless you need to use the internal Ethernet port for other functions that prevents its use for I/O or have more I/O than is supported with the single internal master, I would always prefer Do-more's master over the ERM100.

[franji1]

If you have a lot of OTHER Ethernet stuff going into/out of your DM1E's local Ethernet port, you may want to "isolate" your Ethernet-based I/O (EBC100) by putting it on a physically different network via an ERM module.

For instance, if you connect an HMI or Designer software via the DM1E's Ethernet port, which polls the PLC "as fast as possible", that could affect the Ethernet I/O that is being done at the same time (you may need to adjust your Ethernet I/O poll rates and/or timeout values).  Sadly, there is no "hard rule" that says how much traffic your DM1E can handle - you will want to use the Ethernet I/O Monitor utility available under Designer's Debug menu to help determine that empirically.  (You could use an ECOM100 module for HMI/Designer purposes in lieu of getting an ERM, or possibly use USB or Serial on the CPU for your Designer programming port).

Also, if you have a bunch of older EBC modules (not EBC100), those only work with ERM, not Ethernet I/O.

Note that Ethernet I/O has many advantages over ERM including configurable poll rates, built-in native support of GS-EDRV100s, and ability to configure the fatal error/warning response by Ethernet I/O whenever a slave goes "offline" or has mismatched I/O (ERM has no direct influence over PLC's RUN mode).

[MikeS]

IMO, given the choice between the two options, there aren't any advantages to using the ERM100

it's slower (because the ERM100 is installed in a slot that gets serviced across the backplane) and the Slave's I/O gets mapped into general purpose memory (I/O in the slave base that is connected through the Ethernet I/O Master is mapped into X/Y/WX/WY memory just like local I/O).

The Ethernet I/O master really shines if you are going to be using a CTRIO/CTRIO2 module, interacting with a CTRIO device is far superior to writing ladder logic using the BITs, WORDs, and DWORDs mapped into memory via the ERM100.

[lyndonschroeder]

Thanks to All. Just what I needed.