S7-SoftPLC:Modbus TCP configuration
This driver allows to connect local I/O with the S7-SoftPLC via Ethernet / Modbus TCP. The driver supports the Modbus TCP function codes listed in the chart below. If a slave is supposed to run with the S7-SoftPLC, it should be verified, that it supports the listed Modbus functions. If possible the Modbus function Read/Write Registers (0x17) should be used, since it executes reading and writing in one frame. If a slave does not support this funciton, it has to be created as two slaves. The first configuration reads the inputs, the second writes the outputs. Since this isn't very efficient, the function Read/Write should be preferred. Additionally the driver installs a Status SFC/FC, to monitor the status of the Modbus TCP connection.
Status SFC/FC
| CALL | SFC/FC 193 | |
| IN0 | := 1 | //INPUT INT |
| RET_VAL | := MW 0 | //RESULT INT |
| OUT1 | := MW 2 | //OUTPUT INT |
| OUT2 | := MW 4 | //OUTPUT DWORD |
| OUT3 | := MW 8 | //OUTPUT INT |
| OUT4 | := MW 10 | //OUTPUT DWORD |
| Parameter | Type of Data | Description |
|---|---|---|
| IN0 | INT | Slave number format: 0,1,2,3,...this corresponds to the slave index number, as configured |
| RET_VAL | INT | Returns 0 if a parametrisation does exist.
Otherwise 0x8090 Sonst 0x8090 |
| OUT1 | INT | Bit 0 = 1 connection established
Bit 1 = 1 Error Bit 2...7 reserved Bit 8...15 PLC cycles since last I/O module answer (resetted by Status SFC/FC) |
| OUT2 | DWORD | Parametrised IP address |
| OUT3 | INT | Parametrised port |
| OUT4 | DWORD | Windows-Error-Code |
Most important Windows(32-Bit) network-error messages
| 0x271D / 10013d | Permission denied – Indicates restricted rights or a firewall. |
| 0x2745 / 10053d | Software caused connection abort – Probably defective network connection or no slave available at given address. |
| 0x2746 / 10054d | Connection reset by peer. The slave has disconnected the connection. |
| 0x274C / 10060d | Connection timed out. Timeout on network connection. |
| 0x274D / 10061d | Connection refused. The slave (or a router in-between) has refused the connection. |
| 0x2751 / 10065d | No route to host. The connection to the aimed network can not be established. Network settings and gateway/router settings have to be checked. |
Status word
If successful the BR of the status word is set, OR, STA and /FC are zero.
If failed the BR, OR, STA and /FC of the status word are zero.
