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Profisafe and Scalence X-200IRT

Created by: DSiDvD at: 1/2/2009 9:33 PM (4 Replies)

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1/2/2009 9:33 PM	Rate (0)
DSiDvD Posts: 2 Rating: (0)	We are working on a large Profisafe project with another company. They have some interesting views about switches and safety IO; I need to know whether they are valid or not. The system involves 2 319F CPUs each with a number of ET200S racks each with some safety IO in it. Each CPU controls a different part of the system, but they must communicate with each other too using safety communication. Also, G120 drives will be connected each of the PLCs (they DO wish to daisy chain these). We are NOT doing motion control with any of the drives in the system. Also, 1 of the CPU's will be communicating with 1 touscreen HMI. The company we are working with believes that we need to put a SCALANCE X204IRT or SCALANCE X202-2IRT at every ET200S rack because they feel this will allow us to achieve an advantage (speed or higher communcation rates or lower safety scan times, etc.) over, when daisy chaining, using the copper ports an IM151-3 PN HF or the fiber ports of an IM151-3 PN FO, and when doing a stara X208 or X204-2. The only issue I am aware of is that it is not wise to daisy chain the HMI to a IM151. It should be wired to a switch which is only wired to other switches between it and the CPU, do to the manner in which the HMI accesses IO. Are there ANY advantages (when not doing motion control) to using an IRT switch over the built in switches of the ET200S for our system? Are there any advantages (when not doingmotion control) to using a X200IRT over anX200 switch for our system? If so, what are those advantages? If not, technically, do you gain anything (besides trouble shooting info) when not using a managed switch (X200) over a non-managed switch? (Not that we would do this, but just to be clear.)
DSiDvD Posts: 2 Rating: (0)
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1/3/2009 1:33 PM	Rate (0)
INS Gold Member Joined: 4/6/2006 Last visit: 2/5/2024 Posts: 604 Rating: (56)	Hello, There are at the moment two possible ways of having an advantage when using the IRT Switches. 1. You are using IRT where the use of Cut-Through switching is necessary. That's not your case since you are using ProfiNet RT components. There for using a IRT Switch wil bring to higher costs since the deivces are more expensive and have less ports then the regular X200 switches. 2. You want to use a Ring Redundancy which is released to be used together with ProfiNet RT: It's called Media Redundancy Protocol (MRP). This ring has a faster Ring Recovery time of less 200 ms. with up to 50 devices and is inside the ProfiNet standard. At this moment it's not possible to use this with all the PN IO Devices like Decentral IO since that's not released for such modules on the market at this moment. Having a Panel behind an ET200S, it's possible but I won't advice you to do this due to the possible high communications load which is running over the ET200S Chain. Furthermore be aware of not having more then 10 'hops' behind each other when using a line structure based on PN IO Device. Using Managed an unmanged devices in a mixed way is no problem. But you will loose some of diagnsostic possibilties compared with a complete managed network.
	Best regards, INS
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1/8/2009 10:54 PM	Rate (0)
DSiDvD Posts: 2 Rating: (0)	Thanks for the quick response, INS. Based on what you have said, I've had some time to work on this, and this is what I have proposed: PLC L (A fiber ring between all the X204-2): 1) X204-2 to - 319F PLC - CU240S PN-F daisy chained to CU240S PN-F 2) X204-2 to IM151 PN HF 3) X204-2 to IM151 PN HF 4) X204-2 to IM151 PN HF PLC R: X206-1 (#1) to - 319F PLC - X206-1 (#2) (fiber) X206-1 (#2) to - HMI - IM151 PN HF - IM151 PN HF daisy chained to IM151 PN HF - X208 X208 to - IM151 PN HF - IM151 PN HF daisy chained to IM151 PN HF - IM151 PN HF daisy chained to CU240S PN-F [daisy chained to CU240S PN-F] x 5 The group we are working with wants us to confirm that the two IM151's that are daisy chained to other IM 151s (show above as): - IM151 PN HF daisy chained to IM151 PN HF won't have a slower IO response than if we did this - IM151 PN HF to X208 to IM151 PN HF In other words, as long as we don't daisy chain more than 10 I/O devices (a limit you stated in your response), is there a slowdown when we use the internal IM 151 switches to daisy chain vs. always using a tree/star structure from X200s? Their specific concern deals with some regular inputs we will need to read with an STI in the daisy chained IM151 PN HF. They didn't express issue over speed to the daisy chained drives, but if you would recommend an X208 over daisy chaining the 6 drives off of an IM151, let me know. Thanks for your help on this.
DSiDvD Posts: 2 Rating: (0)
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1/9/2009 9:30 AM	Rate (0)
INS Gold Member Joined: 4/6/2006 Last visit: 2/5/2024 Posts: 604 Rating: (56)	Hello, Placing up to 10 Device in a line is not a problem. But it's interesting to have a look at the amount of data to those devices, are this fully build ET200S Stations or do those only have a couple modules? Furthermore the speed is not a problem mainly the update time. What do you need? Even if it's not placed in a line structure it could be interesting to create different update times for the different modules. This means that if you do this you will lower you network load and you will create more stability in your network. The fastest update time would be 1 ms if you can set this to 2, 4, 6 or even 8 ms this would create a more stabile situation. This not only counts for line structures but for the overal network setup. Otherwise the switch where you are connected with would be very busy. About using a Ring Structure, I agree that's it's an interesting idea to use this because of the Redundancy. But keep in mind that when you do this the Ring Recovery time is 300 ms with HSR (High Speed Redundancy) which means that it could take up to 300 ms to recover the network. If your PN IO Device are set to an update time for 4 ms those will fall of the bus. They will return but since you use Safety you will need to passivated and reintegrate those devices I guess. A solution here could be making sure that the number of retries (Basic setting =3) times the update time in ms is higher then the highest possible Ring Recovery Time (300 ms). 4 ms x 76 Retries = 304 ms 8 ms x 38 Retries = 304 ms This higher setting for retries will mean that it takes a longer time before a device/network failure is detected but you are ensured of a stable working of your network. With MRP (Media Redundancy Protocol) you will have a rcovery time of only 200 ms. This functionality is only available in the Scalance X200IRT Devices according to the manuals. But in the manuals it's already mentioned to be available in the Scalance X200 switches with a firmware > v4.0. ● MRP is supported in ring topologies with up to 50 devices. Exceeding this number of devices can lead to a loss of data traffic. ● The ring in which you want to use MRP may only consist of devices that support this function. This applies, for example, to the following devices: >Industrial Ethernet switches >SCALANCE X-200 as of firmware version V4.0 >SCALANCE X-200 IRT as of firmware version V4.0 See chapter 2.4 of the manual. Industrial Ethernet Switches SCALANCE X-200 Operating Instructions This is interesting for your projectsince then you will need the following retries: 4 ms x51 Retries =204 ms 8 ms x26 Retries =208 ms I checked the web and can't find the fw v4.0 or higher so it seems that it isn't relesed yet.
	Best regards, INS
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2/13/2009 2:33 AM	Rate (0)
Safety1 Posts: 73 Rating: (20)	Hello DSiDvD I am not so sure that Profisafe will work with IRT. Please contact Siemens Hotline to verify this as I have never seen the use of IRT and Safety. You only benefit from IRT if the devices support this feature
Safety1 Posts: 73 Rating: (20)
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