Siemens SIMATIC S7-1200 System Manual page 1247

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Example: communication errors reporting

Communication errors (STATUS = 16#818B) are only reported on the USS_PORT

instruction and not on the USS_DRV instruction. For example, if the network is not properly

terminated then it is possible for a drive to go to RUN but the USS_DRV instruction will show

all 0's for the output parameters. In this case, you can only detect the communication error

on the USS_PORT instruction. Since this error is only visible for one scan, you will need to

add some capture logic as illustrated in the following example. In this example, when the

error bit of the USS_PORT instruction is TRUE, then the STATUS and the

USS_Extended_Error values are saved into M memory. The drive number is placed in

USS_Extended_Error variable when the STATUS code value is hexadecimal 8180, 8184,

8187, or 818B.

Read and write access to drive internal parameters

USS drives support read and write access to a drive's internal parameters. This feature

allows remote control and configuration of the drive. Drive parameter access operations can

fail due to errors such as values out of range or illegal requests for a drive's current mode.

The drive generates an error code value that is returned in the "USS_Extended_Error"

variable. This error code value is only valid for the last execution of a USS_RPM or

USS_WPM instruction. The drive error code is put into USS_Extended_Error variable when

the STATUS code value is hexadecimal 818C. The error code value of

"USS_Extended_Error" depends on the drive model. See the drive's manual for a description

of the extended error codes for read and write parameter operations.

S7-1200 Programmable controller

System Manual, V4.2, 09/2016, A5E02486680-AK

Communication processor and Modbus TCP

13.7 Legacy USS communication (CM/CB 1241 only)

Network 1"PortStatus"port status

and"USS_DRV_DB".USS_Extended_

Errorextended error code values are

only valid for one program scan. The

values must be captured for later pro-

Network 2The "PortError" contact

triggers the storage of the "PortStatus"

value in "LastPortStatus" and

the"USS_DRV_DB".USS_Extended_E

rrorvalue in "LastExtError".