Industry Online Support
Technical Forum
9/3/2009 2:45 PM | |
Posts: 95 Rating: (0) |
I am trying to find an answer as to how many slaves are allowed on the slave side of a y-link bus link. I have found two sources for information, one is an FAQ, http://support.automation.siemens.com/US/view/en/6847578 and the other is the manual (A5E00193841-16)for bus links DP/PA coupler, DP/PA link, and Y-Link. I have attached the page I will reference here. The FAQ indicates there is a maximum of 31 slaves with a byte limit of 244 maximum for all slaves. The page from the manual, section 2.6 of the manual, indicates you can have up to 64 nodes. Which is correct? Step 7 allows the connection of 64 nodes. regards john AttachmentPages from Profibus_DP_PA_Y_link_en[1].pdf (256 Downloads) |
9/4/2009 12:48 PM | |
Joined: 10/7/2005 Last visit: 10/8/2024 Posts: 3024 Rating: (1054) |
Hello John the FAQ is OLD (2001) and refers to to the IM157 (6ES7 157-0AA81-0XA0) which used to be the (redundant) DP link (confusingly enough, PA couplers and Y-Links were also 157 part number back then). Anyhow, assuming you use thenow available IM153-2 (6ES7 153-2BAx1-0XB0) as the (redundant) DP link, you can have up to 64 DP Slaves behind your Y-Link (or up to 64 PA devices across 2 or more PA couplers). Note that the I/O limit of 244 Bytes for the IM153-2 remains as before (it has to, as this is a DP-Slave limit)and that you will need at least TWO repeaters behind your Y-Link if you use the max allowable 64 DP Slaves (max 32 Device per Segment, and Y-Link and repeater "count" as devices). Have a look at the technical spec section at the end of yourDP-PA-Ylink manualtoo for more on this. I hope this helps |
Cheers |
|
Follow us on