Siemens

Connection to a Device

1. Go to the Configure section of the Gateway webpage.
    
2. Scroll down and select OPC-UA Server > Devices.
    
3. On the Devices page, find the blue arrow and click on Create new Device.
    
4. On the Add Device Step 1: Choose Type page, select Siemens S7-1200, and click Next.
   

   There are four modules to choose from

   • Siemens S7-1500
     Which connects to Siemens S7-1500 PLCs over Ethernet.
   • Siemens S7-1200 
     Which connects to Siemens S7-1200 PLCs over Ethernet.
   • Siemens S7-300
     Which connects to Siemens S7-300 PLCs over Ethernet.
   • Siemens S7-400
      Which connects to Siemens S7-400 PLCs over Ethernet.
5. On the New Device page, leave all the default values and type in the following fields:
   Name: S71200
   Hostname: type the IP address, for example 10.20.4.71
6. You can check the box for Show advanced properties? to see the additional settings, but you can keep all the defaults.
7. Click Create New Device.
   The Devices page is displayed showing the Siemens device is successfully created and added to Ignition. The Status will show as Disconnected and then Connected.

Unlike other PLCs, but just like Modbus, Siemens devices do not support browsing, therefore you can not browse the tags by going to the OPC Connections > Quick Client in the Configure section of the Gateway. To see and browse the tags, you need to create the tags manually as described in the Addressing section.

Configuring Siemens Addressing

The S7 protocol does not support tag browsing. Therefore, you must configure all tags in the Designer. This can be done either manually, as needed, or by importing bulk using the Tags CSV import functionality.

To manually specify each address

1. From the Designer, in the Tag Browser, right-click on Tags folder, and then go to New Tag > OPC Tag.
2. In the Tag Editor window, as an example, you can set the following values:
   Name: Tag
   Data Type: Int4
   OPC Server: choose Ignition OPC-UA Server from the dropdown
   OPC Item Path:  [S71200]IW0, the S71200 device name goes in the square brackets then you give the address to PLC which in this example is IW0 (Word at Offset 0 in the Inputs area). The Configuring Siemens Addressing section below, explains how your can construct these addresses.
3. Click OK.
   Now you can see the Temp tag in the Tag Browser.  

Address Syntax

You need a device name plus a tag address to create a tag. The device name is a known, but the tag address needs to be configured. Once you have both the device name and tag address you enter them in the in the OPC Item Path field of the Tag Editor window using the [device_name]address format, where device_name is the name of the device and address is the configured tag address which is described here.

Tag addresses are made up of three different components: Area, DataType, and Offset.

To form an address, you combine syntax for the desired Area and DataType with an Offset into that area.

Offsets 

It is important to note that offsets are absolute. IW0 and IW1 share a byte. To get 2 consecutive, non-overlapping words you need to address IW0 and IW2.

Bits 

Bits are addressed by using the Bit DataType (X) and appending .bit to the end, where bit is in the range [0-7]. When addressing a Bit at a given offset, that offset is always treated as a Byte. 

Strings 

Strings are assumed to be in the S7 string format and have a max length of 210. 

Timers 

Timers are scaled up to a DWord and converted from S5 time format so they can represent the time in milliseconds without requiring any multipliers. When you write to a timer it is automatically converted from milliseconds into S5 time format for you. A DataType is not specified when accessing Timers. 

Counters 

Counters in the PLC are stored in BCD. The driver automatically converts to/from BCD for you and exposes any counter tags as UInt16 values. A DataType is not specified when accessing Counters.