Which is batter, DH+ or ControlNet?

They've graduated approximately within the same class...;)
It depends of the intended application.
DH+ is a Peer-to-Peer communications network while ControNet is a Master-Slave networking application.
Communications rates and bandwith are vastly superior while ControlNet networking (I/O class); CNet communications are truly deterministic and redundancy capable, however, they require anything but perfect media and any configuration/modification/device replacements will require a system shut-down if the communications are of the "scheduled" type and no redundancy is implemented.
Data Highway Plus (DH+) is a lower class communication protocol primarily intended to be used for CPU-to-CPU explicit communications (MSG) and/or CPU-to-HMI integration.
 
pranav.mistry003 said:
Thanks Helliana..

The PLC is about to use in Oil Industry. It will be equipped with about 200 Digital IOs, 2 AIs and 2 AOs. There will be 2 Servers and 3 Workstations for SCADA and as an engineering terminal.
Click to expand...

ControlNet has been around for a long time; it is not "obsolete" by any means, however, it is a Fieldbus afterall...;)
Unless you need a strictly deterministic system, a Safety + Redundant EtherNet/IP networked system is the way to go, especially if this is a new install.
 
dmargineau said:
ControlNet has been around for a long time; it is not "obsolete" by any means, however, it is a Fieldbus afterall...;)
Unless you need a strictly deterministic system, a Safety + Redundant EtherNet/IP networked system is the way to go, especially if this is a new install.
Click to expand...

Thanks Dmargineau,
You've advised me a best way.. All doubts are cleared..

Thanks again with warm regards...(y)
 
Why are you using a PLC5 system on a new project?
Click to expand...

My first reaction. You'll get much better bang for your buck with something from the Logix family (Compact or full). ControlNet would be perfectly at home there as would Ethernet/IP.

I've been under the impression that Ethernet/IP is now deterministic as it's possible to do motion over it now which works pretty good. As far as rock solid dependability though (especially if you don't want to have to share with the IT types) I'd lean toward ControlNet.
 
JesperMP said:
Ethernet/IP is not deterministic ?
Click to expand...

Nope Jesper, it is not; close but not quite there; that's why users still need to write code for monitoring of an EtherNet/IP connection except for EtherNet/IP motion.
RPI stands for "Requested...."; there is no RPI "enforcement" within an EtherNet/IP subnet; CNet NUT (Network Update Time) is permanently enforced by the Keeper- no user "intervention" required.
 
Mickey said:
JesperMP said:
Ethernet/IP is not deterministic ?
Click to expand...
No it is not.
Click to expand...
I think it is. I read some articles (*), and as long as switches are used, and they support IGMP snooping, Ethernet/IP will be deterministic.

*: Dont ask me to link to these articles. It was years ago.

The more recent discussion that goes on HERE is way over my head, but I think it circles around "Ethernet/IP is deterministic" and "Ethernet/IP is in theory not deterministic but in praxis it is".
 
Nice link, Jesper. I would have given the same answer as Mickey, but after reading the excellent posts by Mr. Caro in your link, it appears that statement must be qualified.
 
JesperMP said:
I think it is. I read some articles (*), and as long as switches are used, and they support IGMP snooping, Ethernet/IP will be deterministic.

*: Dont ask me to link to these articles. It was years ago.

The more recent discussion that goes on HERE is way over my head, but I think it circles around "Ethernet/IP is deterministic" and "Ethernet/IP is in theory not deterministic but in praxis it is".
Click to expand...

Jesper,

I am myself more of a theoretician type...:ROFLMAO:

I agree that EtherNet/IP is the ultimate industrial automation networking protocol(practically deterministic), however, it runs on top of the Ethernet electrical layer hence it's still a "first come-first served" data transfer; any managed switching will merely establish priorities and/or "filter" multicast/broadcast data packets for the most efficient transfer to take place.
There isn't any Ethernet "built-in mechanism" to ensure user defined constant data transfer intervals; I guess this is the very reason Ethernet is so fast and flexibly deployable.
The 20 ms Requested Packet is not always delivered every 20 ms; sometimes is being received after 21 ms and most of the time probably in less than 20 ms.
This is where the "deterministic" attribute cannot be applied; a 20 ms RPIed data packet received in 19 ms will do, however, this contradicts the deterministic definition.
A ControlNet Keeper ensures that a 20 ms NUT is always 20 ms; no less, no more.
They are slowly getting there though; Motion over EtherNet/IP is a huge step and probably more will come soon.
According to http://en.wikipedia.org/wiki/Deterministic_algorithm
the result is always the same; the LinkedIn topic "deterministic EtherNet/IP believers" are confusing "Determinism" with "Predictability".
 

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