kb:production:s7-communication:iso-tp
03 ISO TP
aka COPT
| Name | ISO Transport Protocol |
|---|---|
| ISO | ISO DP 8073 |
| RFC | RFC 905 |
The COTP packet is the content (the TPDU) of the TPKT packet. The structure of the packets depends on the type of data sent.
Connection Request
Packet Structure
| ISO TP | PDU | |||||
|---|---|---|---|---|---|---|
| ISO on TCP | TPKT | TPDU | ||||
Contents
| Byte | Value | Description |
|---|---|---|
| Fixed part | ||
| [0] | 0x11 | LI (Length Indicator): Length of Header (17) |
| [1] | 0xE0 | bits 1-4: PDU Type Specification (1110 = CR) bits 5-8: Credit (0000 = non-reliable) |
| [2-3] | 0x00 00 | DST - REF |
| [4-5] | 0x00 01 | SRC - REF (can be set by the client) |
| [6] | 0x00 | CLASS (Class/Extended Format/Flow Control) |
| Variable part | ||
| TPDU Size parameter | ||
| [7] | 0xC0 | param code = 0xC0 |
| [8] | 0x01 | param length = 0x01 |
| [9] | 0x09 | param value: Size (512 = 0x09; 1024 = 0x0A) |
| Calling (Src) TSAP parameter | ||
| [10] | 0xC1 | param code = 0xC1 (calling TSAP) |
| [11] | 0x02 | param length = 2 bytes |
| [12] | 0x01 | param value: Device Group (PG/PC = 0x01) |
| [13] | 0x00 | param value: TSAP ID (eg 0x00) |
| Called (Dst) TSAP parameter | ||
| [14] | 0xC2 | param code = 0xC2 (called TSAP) |
| [15] | 0x02 | param length = 2 bytes |
| [16] | 0x03 | param value: Device Group (OP = 0x02; Others = 0x03) |
| [17] | 0x…… | param value: Slot [bits 0..4] and Rack [bits 5..7] Numbers (see PLC Types) |
Data Transfer
Packet Structure
| ISO TP | Header | User Data | ||||
|---|---|---|---|---|---|---|
| ISO on TCP | TPKT | TPDU | ||||
Header
| Byte | Value | Description |
|---|---|---|
| Fixed part | ||
| [0] | 0x02 | LI (Length Indicator): Length of Header (2) |
| [1] | 0xF0 | bits 1-4: PDU Type Specification (1111 = DT) bits 5-8: Credit (0000 = non-reliable) |
| [2] | 0x80 | bits 1-7: TPDU-NR (0) bit 8: End-Of-Traffic (1) |
User Data
aka S7 PDU
See 04 S7 Comm.
kb/production/s7-communication/iso-tp.txt · Last modified: 2019/12/10 10:29 by joerg.hampel