Siemens S7-300 Serial

6 min

Review the following information for setting up and configuring the Siemens S7-300 Serial driver.

Litmus Edge Compatible Series

Compatibility parameter	Compatible items
Driver type	Serial
Validated devices/series	S7-300

To set up and configure this device in Litmus Edge, you will need to do the following:

Step 1: Set up and Configure the PLC Device

Step 2: Set up the PLC Device in Litmus Edge DeviceHub

Step 3: Configure the List of Registers

Step 1: Set up and Configure the PLC Device

Record the serial communication parameters for the device. Otherwise, use PLC software on your machine to look up these parameters. You use these parameters for setting up the driver in the next step.

Step 2: Set up the PLC Device in Litmus Edge DeviceHub

Configure the following parameters when you Connect a Device with this driver. Update default values to the specific setup of your device.

Parameter	Value
Type	Siemens
Driver	Siemens S7-300 Serial
Communication Port	Local Serial connection file path
Baud Rate	19200
Data Bits	8
Parity	Even, Odd, None
Stop Bits	1
Station	2

Step 3: Configure the List of Registers

When you Add a Tag to the connected device, refer to the following register table and tag parameters.

See the following additional resources if necessary:

Organize Device and Tag Data by Using Metadata

Tag Formula Variables

Register Table

Name	Value Type	Address Format	Max Address	Description
PE	bit, word	DDDDd	40957
PA	bit, word	DDDDd	40957
MK	bit, byte, word, dword, real, counter, timer	DDDDd	40957
DB	bit, byte, sint, word, int, stime, time, date, time_of_day, char, dword, dint, real, string	DDDDDd	327677	Data Block

Tag Parameters

Name: Select a register name from the drop-down list. The available options depend on the names in the register table.

Value Type: Select a data type from the drop-down list. The available options depend on the register name selected.

Polling Interval: Enter a value in seconds. This determines how often the tag should poll the register for data.

Tag Name: Enter a name for the tag.

Description (Optional): Enter a description for the tag.

Address: Enter a tag address. The value must in the decimal format, within the allowed min/max range. Omit the leading zeros. The device might use the decimal (D), hexadecimal (H), or octal (O) address format. See the Register Table at the bottom of the dialog box. For Bit tags, append the bit address without the bit separator. The lowercase letters in the address format indicate how many digits you should enter in the Bit address.

Count: Enter the number of register values to read. A count higher than 1 will generate an array of values from the address value configured and respective subsequent address values.

DB: Enter the data block number of the tag.

Tag Formula: Enter a formula for the tag to process the generated data. Two variables are permitted: value (current tag value) and timestamp (current tag UNIX time in milliseconds). The following math functions are available:

sqrt

power: power(x) performs the operation 10^x.

log: log(x) is the natural logarithm (the logarithm is in base e).

exp: exp(x) performs the operation e^x.

Only Publish on Change of Value: Select the checkbox to customize NATS messages to be published only when the value parameter changes from a previous value to a new one. Change of Value only applies to boolean, numeric (such as int or float), and simple string data types. It does not apply to complex types, such as JSON or array. Poll-once topics will not be affected by Change of Value settings. These topics will still only see a single message.

Meta Data: Metadata summarizes basic information about data. This feature allows you to define key-value pair data for the device output payload later on. It can then be used to find, use, and reuse particular instances of data.

Note: If you use special characters in meta data key names, the special characters are replaced with underscore characters in the payload. This can cause two key names to be combined into one. For example, configuring the key names a**b and a&&b will cause only one key name to be created (a__b).