Unity pro modicon and IO scanning etc - Experts?

[admanirv]

Hi,

I have two quantum modicon PLC's over ethernet with an NOE card, i wish to read one REAL value from one PLC into another that's it really. I have read the schnedeir manual but doesnt help too much, firstly i need IO scanning setup on both PLC's?

Can anyone give me a good run down (start to finish) how to do this using IO scanning having problems (data types, setup in both PLCS) as can't get it to work, they are both on same network with unique IP addresses.

Also when i enable global data, i can not build the project comes up with a blue tick!?

I also note someone quoting "in stb the digital input address is 45392. Inorder to read this address in plc we write 45392-40001=5391 so we write in "Read Slave Index" column 5391 - i dont undestand this logic/nor what it means? but i see Slave index colum in IO scanner.

Thanks

 

[Saffa]

Hi,

OK so here we go:

On the "slave" PLC, make sure the tag you want to read is located (i.e. has an address, like %MW100). Since you're reading a real, that's two words long. You don't need to configure IOScanning on this PLC.

On the "master", i.e. the PLC reading the value, set up a line in the IOScanner with:
IP Address - address of the slave
Unit ID - I can't remember off the top of my head what the Unity ID of the NOE is for the quantum, check the manual otherwise try 0 or 255 and work down from there.
slave Syntax - this is the addressing style. Select IEC 0 to match the %MW style i described for the slave, to keep things simple.
health timeout and repetitive rate - select as appropriate for your system.
RD Master object - this is the memory location in the master PLC where the data being read is placed. it's automatically populated depending what you set the "Master %MW zones Read Ref" to, this is just above the IOScanner list.
RD ref slave - in my example, this would be set to %MW100 to match the slave.
RD length - for 1 real, set this t 2. I'd set aside more room for later expansion, as you can't change this online (requires offline build and download)
Leave the write stuff as is if you're not writing words.

disable global data, you dont need it.

that's all you need to do. You should see your data in the mapped %MW location if you've got it all set up right.

I also note someone quoting "in stb the digital input address is 45392. Inorder to read this address in plc we write 45392-40001=5391 so we write in "Read Slave Index" column 5391 - i dont undestand this logic/nor what it means? but i see Slave index colum in IO scanner.

Thanks

The comment above relate to STB I/O which in the manuals, use modbus style addressing, i.e. 45392. in IEC style addressing, this would be %MW5391, i.e. 45392 - 40001. 40001 is the start address of holding registers in modbus.

hope that helps. I don't actually have any quantums running Unity (unfortunately the two I do have are pre-unity...) but i use IOScanning on the M340's and Premiums, it should be identical.

 

[admanirv]

Okay thanks very much!

I'll let you know how i get on.

So my Master is the PLC that has that data i want, and Slave data i want to read from the master PLC?

And i should not use Modbus style address i should use IEC?

Any ideas on the blue tick symbol? means i can not build!

Thanks

 

[Saffa]

Slave PLC has the data you want. Master PLC will be the PLc reading the data.

yup, use IEC style addressing - that's consistent with Unity's addressing structure.

what is the error message displayed when you try and build? have you disabled global data and then closed the configuration tab? Unity will normally ask you if you want to accept the changes, and it won't let you build until that's done. I normally close all open windows before attempting to build.

 

[chud]

Pm me your email address and i will send you a pdf explaining it

 

[admanirv]

Hi,

I can't build it, option is greyed out. I analyse project and comes up with no errors but notice ethernet connection has a blue tick on it which is not normal.

Thanks chud I've done that.

Thanks

 

[chud]

Close the ethernet section first. It will ask for you to validate the changes. Then only build

 

[chud]

If I were you I would rather use the Global Data. Both IO scanning and global data will require you to download and stop the plc anyways. Assign about 100 or 500 words to the global data. So in future you dont have to stop the plc to make changes to the IO scanning.

 

[Saffa]

I dunno, i'm a fan of IOScanning. I feel like I then have more control over what exactly is getting put on the wire and when. But maybe that's just my own silly perception!

 

[chud]

Not at all. That is very understandable.

Global Data has an advantage over client/server services when more than one subscriber is
receiving the same data since only one transaction is necessary for all subscribers to receive the
data. There are two benefits:
 the reduction of overall network traffic
 tighter synchronization of multiple subscribers

I just like to assign global data to a bunch unlocated memory in the beginning of a project(Dont have to use physical registers).
And i have yet to see the global data comms fail (knock on wood).
But IO scanning works just fine aswell

Anyway in the manual I emailed you admanirv both are explained

 

[robertkjonesjr]

I like global data too, but it seems to be the red-headed step child of Schneider's Ethernet protocols. Their new Ethernet devices which support EtherNet/IP do not support global data, which would tell me perhaps they are phasing it out? If it's a brand new install, though I like global data for it's simplicity, I would probably choose EtherNet/IP or Modbus as these are likely to be supported far into the future.

Chud listed some of the pros, but there are some cons as well:

1. Multicast usually should be managed with IGMP or GMRP. Schneider is not consistent with this - Quantum/Premium support both of these management protocols, but M340 only supports GMRP. So if you plan to mix architectures, you need to consider managed switches that support these multicast management mechanisms and choose a common one that is supported by all devices in your system.
2. The versions across the line are not exactly the same, either - you will notice that with Quantum/Premium you publish data at a given number of scans; with M340 it is time based. This is significant if you want the very best update times: since new data is only available at end of scan, sending data at end of scan is best case update. However, with M340, since there is a time component, there may be a delay in sending new data if end of scan does not align with the sending period. Usually not a big deal.
3. I also noticed that M340 is a simpler design as it always publishes data, as it is configured. But Quantum/Premium do not. If there is no subscriber, then production will stop, so there must be some type of handshake going on. M340 will just keep publishing, whether a subscriber exists or not.
4. From a performance standpoint, all three of Schneider protocols perform the same given the same set of configurations, such as scantime, data communications period, etc.

It is true multicast can reduce overall network traffic, but realize *usually* this is never an issue. Industrial Ethernet networks tend to be over provisioned, which means there is plenty of excess capacity available. Of course there are exceptions, but the vast majority have very low utilization. Good architecture design for Cybersecurity helps with this too, utilizing the concepts of network separation and segmentation.

 

[Lare]

Pm me your email address and i will send you a pdf explaining it

chud, can you email this manual also for me...

p.s pm sended