Understanding network.scanner.search

I’m using Raspberry Pi with MCP2515 connected to a network consisting of two Delta servo drives. I am trying to get this example to work:

network.scanner.search()
time.sleep(0.05)
for node_id in network.scanner.nodes:
    print("Found node %d!" % node_id)

As far as I can tell, network.scanner.search sends SDO message to all possible nodes on the bus (1-128).

for node_id in range(1, limit + 1):
            self.network.send_message(0x600 + node_id, sdo_req)

But how does it actually find out there are nodes present (which method in the class)? i.e. which method is listening for a response message from the node?

[christiansandberg]

You can create a can.Listener and attach it to Network.listeners.

class MyListener(can.Listener):
    def on_message_received(self, msg):
        print(repr(msg))

network.listeners.append(MyListener())

[christiansandberg]

The NodeScanner.on_message_received method collects messages coming from slave nodes and is called from Network.notify which receives all messages coming in from the bus.