LSS (Layer settings service) is an extension to CANopen described in CiA DSP 305. The interface is described in CiA DS 309 3.0.0 (ASCII mapping). LSS allows the user to change node ID and bitrate, as well as setting the node ID on an unconfigured node.

LSS uses the the OD Identity register (0x1018) as an unique value to select a node. Therefore the LSS address always consists of four 32 bit values. This also means that LSS relies on this register to actually be unique. (vendorID, productCode, revisionNumber and serialNumber must be configured and unique on each device.)

Preparation for testing on Linux virtual CAN

LSS can be tested on Linux virtual CAN, similar as in gettingStarted.md.

Open terminal, setup vcan0 and cd to CANopenNode directory.
Make some unique CANopen devices:
- Edit CO_OD.c, change initialization for identity, for example change line to /*1018*/ {0x4, 0x1L, 0x2L, 0x3L, 0x4L},
- make
- mv canopend canopend4
- Edit CO_OD.c, for example: /*1018*/ {0x4, 0x1L, 0x2L, 0x3L, 0x5L},
- make
- mv canopend canopend5
- Repeat this step and create three further "unique" CANopen devices.
Clear default OD storage file. We will use default (empty) storage for all instances:
- echo "-" > od_storage
Run "master" with command interface and node-id = 1. Note that this device has enabled both: LSS master and LSS slave. But LSS master does not 'see' own LSS slave.
- make
- ./canopend vcan0 -i1 -c "stdio"
Run one CANopen device with node-id=22 in own terminal:
- ./canopend4 vcan0 -i22
Run other unique CANopen devices with unconfigured node-id, each in own terminal:
- ./canopend5 vcan0 -i0xFF
- ./canopend6 vcan0 -i0xFF
- ./canopend7 vcan0 -i0xFF
- ./canopend8 vcan0 -i0xFF
Note that lss_store does not work in this example. For it to work, OD storage must be used properly.

Typical usage of LSS

Changing the node ID for a known slave, store the new node ID to eeprom, apply new node ID. The node currently has the node ID 22.
```
 help lss

 lss_switch_sel 0x00000001 0x00000002 0x00000003 0x00000004
 lss_set_node 10
 lss_store
 lss_switch_glob 0
 22 reset communication
```
Note that the node ID change is not done until reset communication/node.
Changing the node ID for a known slave, store the new node ID to eeprom, apply new node ID. The node currently has an invalid node ID.
```
 lss_switch_sel 0x00000001 0x00000002 0x00000003 0x00000005
 lss_set_node 11
 lss_store
 lss_switch_glob 0
```
Note that the node ID is automatically applied. This can be seen on candump.

LSS fastscan

Search for a node via LSS fastscan, store the new node ID to eeprom, apply new node ID
```
 _lss_fastscan

 [0] 0x00000001 0x00000002 0x00000003 0x00000006

 lss_set_node 12
 lss_store
 lss_switch_glob 0
```
To increase scanning speed, you can use
```
_lss_fastscan 25
```
where 25 is the scan step delay in ms. Be aware that the scan will become unreliable when the delay is set to low.

We won't configure this node now, reset LSS. Now we have 1+3 nodes operational in our example.
```
lss_switch_glob 0
```

Auto enumerate all nodes

Auto enumerate all nodes via LSS fastscan. Enumeration automatically begins at node ID 2 and node ID is automatically stored to eeprom. Like with _lss_fastscan, an optional parameter can be used to change default delay time.
```
 lss_allnodes

 # Node-ID 2 assigned to: 0x00000001 0x00000002 0x00000003 0x00000007
 # Node-ID 3 assigned to: 0x00000001 0x00000002 0x00000003 0x00000008
 # Found 2 nodes, search finished.
 [0] OK
```
To get further control over the fastscan process, the lss_allnodes command supports an extended parameter set. Auto enumerate all nodes via LSS fastscan. Set delay time to 25ms, set enumeration start to node ID 7, do not store LSS address in eeprom, enumerate only devices with vendor ID "0x428", ignore product code and software revision, scan for serial number
```
 lss_allnodes 25 7 0 2 0x428 1 0 1 0 0 0
```
The parameters are as following:
- 25 scan step delay time in ms
- 7 enumeration start
- 0 store node IDs to eeprom; 0 = no, 1 = yes
- 2 vendor ID scan selector; 0 = fastscan, 2 = match value in next parameter
- 0x428 vendor ID to match
- 1 product code scan selector; 0 = fastscan, 1 = ignore, 2 = match value in next parameter
- 0 product code to match (ignored in this example)
- 1 software version scan selector; 0 = fastscan, 1 = ignore, 2 = match value in next parameter
- 0 software version to match (ignored in this example)
- 0 serial number scan selector; 0 = fastscan, 1 = ignore, 2 = match value in next parameter
- 0 serial number to match (not used in this example)

Note that only unconfigured nodes (those without a valid node ID) will take part in fastscan!