The result error code (a 16 bit value) is composed by two fields, as in figure:
The first 8 bits (2 nibbles) represent a TCP/IP error. The last two nibbles represent an S7 protocol error
TCP Errors table
|
Mnemonic |
HEX |
Meaning |
|
errTCPConnectionFailed |
0x0001 |
TCP Connection error. |
|
errTCPConnectionReset |
0x0002 |
Connection reset by the peer. |
|
errTCPDataRecvTout |
0x0003 |
A timeout occurred waiting a reply. |
|
errTCPDataSend |
0x0004 |
Ethernet driver returned an error sending the data. |
|
errTCPDataRecv |
0x0005 |
Ethernet driver returned an error receiving the data. |
|
errISOConnectionFailed |
0x0006 |
ISO connection failed. |
|
errISONegotiatingPDU |
0x0007 |
ISO PDU negotiation failed. |
|
errISOInvalidPDU |
0x0008 |
Malformed PDU supplied. |
S7 Errors table
|
Mnemonic |
HEX |
Meaning |
|
errS7InvalidPDU |
0x0100 |
Invalid PDU received. |
|
errS7SendingPDU |
0x0200 |
Error sending a PDU. |
|
errS7DataRead |
0x0300 |
Error during data read |
|
errS7DataWrite |
0x0400 |
Error during data write |
|
errS7Function |
0x0500 |
The PLC reported an error for this function. |
|
errBufferTooSmall |
0x0600 |
The buffer supplied is too small. |
I made this division because in presence of a TCP error the Client should be disconnected and re-connected.
It’s easy knowing this by masking the Hi-byte of the error code.