Introduction

The Siemens S7 Connector communicates with the Siemens S7300/400 or S71200/1500 PLC of the machine controller. This communication allows us to monitor data stored in the PLC data block memory for processing by the MachineMetrics platform.

Topics Covered In This Article

• S7 PLC Compatibility
• Gathering Memory Locations Required For Connector
• Connector Configuration
• Data Mapping

S7 PLC Compatibility

S7 300/400

The S7300 and S7400 PLC’s fully support the protocol communication leveraged by this connector.

S7 1200/1500

Only basic data transfer is allowed when communicating with the S71200 and S71500 controllers. Particularly to access a data block in S71500 some additional settings are needed on the PLC side to be configured via TIA Portal.

1. Only global data blocks can be accessed

2. The Optimized Block Access setting must be OFF

3. The access level must be “full” and the connection mechanism must allow “GET/PUT”

Monitoring NCK Values

Numeric Control Kernel (NCK) variables must first be mapped to PLC Memory using a tool such as NCVar Selector for 840D SL machine controllers or similarly loaded into PLC memory by a PLC technician using the controller appropriate utility or programming tools. Once this has been done the values can then be targeted and read with the connector from the PLC.

Important: Variables from the NCK that are not mapped into a data block in PLC memory cannot be reached or read by the MachineMetrics connector.

Locating PLC and NCK Variables

The assignment of names to variables is described in in the service and PLC programming manuals for the target Siemens machine. Parameters that are already loaded into a data block in PLC memory visible in TIA Step7/Simatic Manager can be accessed directly without any mapping.

Any NCK variables identified by the service manuals for the machine must first be mapped to the PLC as indicated above.

Gathering Memory Locations Required For Connector

We need the following columns for each desired monitored variable:

• Data block

• Offset

• Data Type

• Bit Index (if bit/bool type)

• Length (if string type)

This is best communicated by providing your MachineMetrics customer success manager liaison with a tabulated representation of the desired data and their corresponding PLC memory locations.

Example)

If you have questions about the configuration process, please reach out directly to your customer success manager or contact support@machinemetrics.com. 

Connector Configuration

Once all values have been identified and communicated, they can be configured in the connector configuration for the Siemens S7 Connector. The connector configuration can be located using the Machine-Settings instructions.

Below we see an example of the configuration for the above values:

Connector Configuration Data Types

• bit or bool

  • requires bit field

• byte

• word or int (16-bit integers)

• dword or dint (32-bit integers)

• real or double or float

• string

  • requires length field

Data Mapping

After configuring the variables to be monitored, they can then be data mapped in the MachineMetrics application. See Mapping Data

If you have questions about this process, please reach out directly to your customer success manager or contact support@machinemetrics.com.