No.     Time        Source                Destination           Protocol Info
      5 4.631895    dhcpf.fam.tuwien.ac.at 239.255.255.253       SRVLOC   Service Request, V2 XID - 1

Frame 5: 113 bytes on wire (904 bits), 113 bytes captured (904 bits)
Ethernet II, Src: 128.130.51.75 (08:00:27:51:a4:a2), Dst: IPv4mcast_7f:ff:fd (01:00:5e:7f:ff:fd)
Internet Protocol, Src: dhcpf.fam.tuwien.ac.at (128.130.51.75), Dst: 239.255.255.253 (239.255.255.253)
User Datagram Protocol, Src Port: pago-services1 (30001), Dst Port: svrloc (427)
    Source port: pago-services1 (30001)
    Destination port: svrloc (427)
    Length: 79
    Checksum: 0x6f8b [validation disabled]
Service Location Protocol
    Version: 2
    Function: Service Request (1)
    Packet Length: 71
    Flags: 0x2000
    Next Extension Offset: 0
    XID: 1
    Lang Tag Len: 2
    Lang Tag: en
    Previous Response List Length: 0
    Service Type Length: 38
    Service Type List: service:KMRealTWScan0200.KONICAMINOLTA
    Scope List Length: 7
    Scope List: default
    Predicate Length: 0
    SLP SPI Length: 0

0000  01 00 5e 7f ff fd 08 00 27 51 a4 a2 08 00 45 00   ..^.....'Q....E.
0010  00 63 80 e6 00 00 01 11 94 d9 80 82 33 4b ef ff   .c..........3K..
0020  ff fd 75 31 01 ab 00 4f 6f 8b 02 01 00 00 47 20   ..u1...Oo.....G 
0030  00 00 00 00 00 01 00 02 65 6e 00 00 00 26 73 65   ........en...&se
0040  72 76 69 63 65 3a 4b 4d 52 65 61 6c 54 57 53 63   rvice:KMRealTWSc
0050  61 6e 30 32 30 30 2e 4b 4f 4e 49 43 41 4d 49 4e   an0200.KONICAMIN
0060  4f 4c 54 41 00 07 64 65 66 61 75 6c 74 00 00 00   OLTA..default...
0070  00                                                .

HDDTwain: Same request, only different type:
    Service Type List: service:KMHDDTWScan0200.KONICAMINOLTA