gos7

Implementation of Siemens S7 protocol in golang

Overview

Since years, there are tons of driver/connector in both commercial and open source that support connect to S7 family PLC devices. GoS7 is just simple missing pieces in S7 protocol which implementing in with pure Go(aka golang) with a strongly faith that low-level communication would be impelement by low-level programming language which proximity to binary and memory.

Functions

AG:

Read/Write Data Block (DB) (tested)
Read/Write Merkers(MB) (tested)
Read/Write IPI (EB) (tested)
Read/Write IPU (AB) (tested)
Read/Write Timer (TM) (tested)
Read/Write Counter (CT) (tested)
Multiple Read/Write Area (tested)
Get Block Info (tested)

PG:

Hot start/Cold start / Stop PLC
Get CPU of PLC status (tested)
List available blocks in PLC (tested)
Set/Clear password for session
Get CPU protection and CPU Order code
Get CPU/CP Information (tested)
Read/Write clock for the PLC Helpers:
Get/set value for a byte array for types: value(bit/int/word/dword/uint...), real, time, counter

Supported communication

TCP
Serial (PPI, MPI) (under construction)

How to:

following is a simple usage to connect with PLC via TCP

const (
	tcpDevice = "127.0.0.1"
	rack      = 0
	slot      = 2
)
// TCPClient
handler := gos7.NewTCPClientHandler(tcpDevice, rack, slot)
handler.Timeout = 200 * time.Second
handler.IdleTimeout = 200 * time.Second
handler.Logger = log.New(os.Stdout, "tcp: ", log.LstdFlags)
// Connect manually so that multiple requests are handled in one connection session
handler.Connect()
defer handler.Close()
//init client
client := gos7.NewClient(handler)
address := 2710
start := 8
size := 2
buffer := make([]byte, 255)
value := 100
//AGWriteDB to address DB2710 with value 100, start from position 8 with size = 2 (for an integer)
var helper gos7.Helper
helper.SetValueAt(buffer, 0, value)  
err := client.AGWriteDB(address, start, size, buffer)
buf := make([]byte, 255)
//AGReadDB to address DB2710, start from position 8 with size = 2
err := client.AGReadDB(address, start, size, buf)
var s7 gos7.Helper
var result uint16
s7.GetValueAt(buf, 0, &result)

References

libnodave http://libnodave.sourceforge.net/
snap7 http://snap7.sourceforge.net/
tarm serial library https://github.com/tarm/serial
Simatic Open TCP/IP Communication via Industrial Ethernet from Siemens(doku)
SIMATIC NET FDL-Programmierschnittstelle (doku)
Elementary Data Types from Siemens (doku)

Simatic, Simatic S5, Simatic S7, S7-200, S7-300, S7-400, S7-1200, S7-1500 are registered Trademarks of Siemens

License

https://opensource.org/licenses/BSD-3-Clause