s7-1200 to slave (s7-1200 or et200S)

Hi!

This is the first time I try to establish a network and I will eventually implement this at the customer site.

I will have one s7-1200 master and 3*s7-1200 (this is existing and it have to be s7-1200), then I will have basicly 3 data collecting units.

This is where my question is:

First:
To have s7-1200 as slave I will have more possibilities in the data collecting end. I can configure GET/PUT, T_Blocks or with firmware v4 I can use I-Device

Second:
ET200S Profinet , pretty straight forward.


What are the pros and cons with the diffrent solution?

ET200S seems like an easy solution but not as versatile as the s7-1200 solution. Easy to program to.

s7-1200.
I have succesfully made connection with GET/PUT and with T_Block.
But with the T-block, is this a good way doing a type of I/O communicating?
I read this in the manual:

When sending data (rising edge at the REQ parameter), the CONT parameter must have the value "1" in order to establish or maintain a connection. The data to be sent must not be edited until the send job is completed

This seems to be a quite a downfall for this solution.

The get and put seems (from what I've read) a better solutions since it doesn't say anything about changing the data when it executes.

I haven't had the opportunity to test the I-Device since I haven't got two v4 PLCs. But how is this? This seems like a good solution compared to ET200S?
But I have configured it in the TIA portal, but how do I access the tags I have configured here?

Thanks for your tips and help!

/Tim

How does the tags work when I configure an I-device with s7-1200?

As you see I have Q100 and I100 in transfer area. Do I just use them like I100.0 (linked to Q100.0) in the TIA portal? I mean, they are not linked to actual inputs and outputs on my cpu? I haven't found a guide for this.

Yes, you use remote I/O direct like local I/O. You can transfer various data (real, dint...).

But slightly diffrent?

On a ET200S for example I have a +24VDC signal wired to I0.0, this is transfered directly to my s7-1200 over profinet. And I can read that out as an IX.X

On the s7-1200 I-Device I would have a +24VDC signal wired to I0.0, but this is not transfered to the Master directly. I must in this case do a simple rung:

I0.0 Q100.0
--||------( )----

This is then transfered to my master (Q100.0 -> I100.0)

To set output Q0.0 in my master I would have to do another rung.

I100.0 Q0.0
-||-------( )--

Is this correct?

Yes, on Profinet, at IO device you must program your outputs to have some function, then those outputs are read in Controller as inputs.
At DP ET200 (with no CPU) you read direct process image of signals connected to DIs.

You choose CPU as Profinet IO device if you have a need for data processing there, or if there must be a HMI. If you only want to transfer some signals remotely, you can use ET200.

Thanks alot for the answers!

Now when the new s7-1200 v4.0 support I-Device. Will the ET200 be more and more uncommon? Atleast for me, the ET200 is more expensive then the s7-1200. So why do ET200? (This is Profinet based, I understand that if you have profibus the s7-1200 would be more expensive)

Suppose that you have a node with 256DI to be transfered. You can not use S7-1200 (you can connect max 8 modules of 16DI = 128DI), you must use ET200 (8 modules of 32DI) or ET200S (32 modules od 8DI). ET200 will not be shut down becouse of S7-1200.

Ah, didn't think of that. We dont work with that kind of numbers

I think the products that are intended as remote IO have better device diagnostics available than the 1200 as well. They have wiring type diagnostics for short circuits, broken wires, etc, as well as maintenance diagnostics for module faults.

Not always important for a small machine, but in a big plant, these sorts of diagnostics can save a huge amount of downtime.

Ah, I will certainly take that into consideration, thansk!

Another question:

Based on this comment: Yes, you use remote I/O direct like local I/O. You can transfer various data (real, dint...).

Say I have a Dint that takes on 4 bytes. Am I correct when I assume that I can transfer this to over I-Device?

I have Dint in a datablock in master, transfer it to I adresses (don't know what I adress, never work with them) and then I get it as Q adresses in my I-Device?

Yes. In IO device (slave), program example "move number 212 to QD10". Then, if you exchange QB10-14 via Profinet to IB12-15 in Controller (master), you will read number 212 at ID12 in controller (master).

Perfect thanks alot!

How does the communication work with my s7-1200 I-Device configuration?
If the communication is lost, is all my recieved information set to 0 ? Or is it retained?
I guess it is set to 0?

In contrast to for example T_blocks. If I transfer T_Send to T_Rcv , my slave will retain when the communication is lost.
I have to manually reset the information I get through T_RCV. Or how is this usually done?

At IO Controler, use block "DeviceStates" and read proper bit in StatusArray(0..2047) (status of IO devices number 1..2047) to evaluate state of your IO device. If bit is ON, do not use data becouse data is invalid (no connection).

Homer_BL said:

At IO Controler, use block "DeviceStates" and read proper bit in StatusArray(0..2047) (status of IO devices number 1..2047) to evaluate state of your IO device. If bit is ON, do not use data becouse data is invalid (no connection).

Click to expand...

Ah, thanks alot. Does this also apply to ET200 ? Or do they automaticly turn to 0?

/Tim