Aufbau eines Connection Confirm TPDUs
| Byte | Description | ||
| 0-3 | ISO-TCP header | ||
| 4 | length (in byte) of TPDU header (without this byte and possible user data) | ||
| 5 | CC code (1101) & credit (always 0000) | Fixed Part | |
| 6-7 | destination reference | Fixed Part | |
| 8-9 | source reference | Fixed Part | |
| 10 | class option (always class 0) | Fixed Part | |
| 11 | 0xC0 (code: TPDU size) | Variable Part | |
| 12 | 0x01 (length of bytes following) | Variable Part | |
| 13 | TPDU size (as exponent to base of 2) | Variable Part | |
| 14 | 0xC1 (code: calling TSAP-ID) | Variable Part | |
| 15 | 0x02 (length of id) | Variable Part | |
| 16 | 0x02 (unknown function; part of TSAP-ID) | Variable Part | |
| 17 | TSAP-ID (rack & slot) | Variable Part | |
| 18 | 0xC2 (code: called TSAP-ID) | Variable Part | |
| 19 | 0x02 (length of id) | Variable Part | |
| 20 | 0x02 (unknown function; part of TSAP-ID) | Variable Part | |
| 21 | TSAP-ID (rack & slot) | Variable Part |
Rack & Slot
Die Kommunikationseinheit einer SPS wird über eine Bauträgernummer und einen Steckplatz identifiziert. Diese sind Teil der TSAP-ID und werden wie folgt gebildet:
| Baugruppenträger | 0 | 1 | 2 | 3 | 4 | 5 | |
| Steckplatz | |||||||
| 0 | 0x00 | 0x20 | 0x40 | 0x60 | 0x80 | 0xA0 | |
| 1 | 0x01 | 0x21 | 0x41 | 0x61 | 0x81 | 0xA1 | |
| 2 | 0x02 | 0x22 | 0x42 | 0x62 | 0x82 | 0xA2 | |
| 3 | 0x03 | 0x23 | 0x43 | 0x63 | 0x83 | 0xA3 | |
| 4 | 0x04 | 0x24 | 0x44 | 0x64 | 0x84 | 0xA4 | |
| 5 | 0x05 | 0x25 | 0x45 | 0x65 | 0x85 | 0xA5 |