Sinamics V20 USS comms to S71500

Greetings everyone, I have a TIA V16 project in which I set up 7 drives to communicate with an S7 1500 controller via RS485 using USS protocol. The drives are Simatic V20s daisychained to the bus and are properly terminated with resistors. I use the USS DRIVE CONTROL 31 function block for each drive all located in a single FC and all using the same single instance DB as recommended by Siemens. I then call this FC containing the FBs every 120ms from the MAIN OB. I then call the USS PORT SCAN 31 function in a cyclic OB set at 70ms cycle time. In each V20 i use PZD word length of 2 and a PKW of 4. Both setpoint and commands are sent through USS. What I have observed is every time take out incoming power to any one of the VFDs, the rest of them get F72 comms error and fail to communicate with the PLC. Is this behaviour normal? What causes it? I use an RS485/ 422 PtP BA module sending data at 19200bps. Strangely enough it doesn't show any fault even though the diagnostics interupt setting is enabled on it. What I noticed is that as I was setting up the VFDs one by one, the F72 fault on the BOPs only pops up on an already configured drives. So, the VFDs that hadn't been commissioned yet for RS485, but were already physicaly terminated/ connected to the PLC, didn't fault the bus when they were powered down. They only faulted the bus upon switching them off only after RS485 activation (post commissioning).
 
With my experience of Siemens, I would hazard a guess the USS protocol is causing the symptoms you describe.
It wouldn't surprise me that fault diagnosis in the protocol ignores non-configured drives, but gives errors on the equivalent of power failure on the others.

Early serial data protocols for the S5 series processors also did strange things for no obvious reason. I put down to the way Germans think...
 
Greetings everyone, I have a TIA V16 project in which I set up 7 drives to communicate with an S7 1500 controller via RS485 using USS protocol. The drives are Simatic V20s daisychained to the bus and are properly terminated with resistors. I use the USS DRIVE CONTROL 31 function block for each drive all located in a single FC and all using the same single instance DB as recommended by Siemens. I then call this FC containing the FBs every 120ms from the MAIN OB. I then call the USS PORT SCAN 31 function in a cyclic OB set at 70ms cycle time. In each V20 i use PZD word length of 2 and a PKW of 4. Both setpoint and commands are sent through USS. What I have observed is every time take out incoming power to any one of the VFDs, the rest of them get F72 comms error and fail to communicate with the PLC. Is this behaviour normal? What causes it? I use an RS485/ 422 PtP BA module sending data at 19200bps. Strangely enough it doesn't show any fault even though the diagnostics interupt setting is enabled on it. What I noticed is that as I was setting up the VFDs one by one, the F72 fault on the BOPs only pops up on an already configured drives. So, the VFDs that hadn't been commissioned yet for RS485, but were already physicaly terminated/ connected to the PLC, didn't fault the bus when they were powered down. They only faulted the bus upon switching them off only after RS485 activation (post commissioning).
Hi

Are you sure about PKW value/setting ...Oem manual show other value can you developp ..
 
CN010 at 19200 bps
try a lower rate 9600 and connect one drive ....terminated...correct type of cable. That's where I would start, get one going first.
In the end, it's going to be something simple...you just have to find it,,, unfortunately, you are dealing with kit that has nuances in how you interpret the manuals.
Serial comms can be a painful exercise in setting up and usually boils down to something embarrassingly simple that is staring you in the face.
 
Greetings everyone, I have a TIA V16 project in which I set up 7 drives to communicate with an S7 1500 controller via RS485 using USS protocol. The drives are Simatic V20s daisychained to the bus and are properly terminated with resistors. I use the USS DRIVE CONTROL 31 function block for each drive all located in a single FC and all using the same single instance DB as recommended by Siemens. I then call this FC containing the FBs every 120ms from the MAIN OB. I then call the USS PORT SCAN 31 function in a cyclic OB set at 70ms cycle time. In each V20 i use PZD word length of 2 and a PKW of 4. Both setpoint and commands are sent through USS. What I have observed is every time take out incoming power to any one of the VFDs, the rest of them get F72 comms error and fail to communicate with the PLC. Is this behaviour normal? What causes it? I use an RS485/ 422 PtP BA module sending data at 19200bps. Strangely enough it doesn't show any fault even though the diagnostics interupt setting is enabled on it. What I noticed is that as I was setting up the VFDs one by one, the F72 fault on the BOPs only pops up on an already configured drives. So, the VFDs that hadn't been commissioned yet for RS485, but were already physicaly terminated/ connected to the PLC, didn't fault the bus when they were powered down. They only faulted the bus upon switching them off only after RS485 activation (post commissioning).
Can you tell us ...What is the value for P2014 parameter ......it seems that this pronblem is related to the correct or not value on this parameter...
 
Can you tell us ...What is the value for P2014 parameter ......it seems that this pronblem is related to the correct or not value on this parameter...
I currently have set it at 1800ms, I have also experimented with 10000ms before with no success to changing the bus issue on powering down 1 drive
 
WHAT about TO CHECK PARAMETERS LIKE P2023 & r2024 TO r2037....I guess that the installed configuration is not correct ...it seems ..so sharing that configuration can be better view for better support
 
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