Sercos distinguishes two types of parameters:
oS parameters which are defined by Sercos.
oP parameters which are not defined by Sercos, but are defined by the vendor of a Sercos device.
A Sercos parameter is often referred to as IDN (identification number). However, the IDN is only one of multiple data block elements (DBE) constituting a Sercos parameter. A Sercos parameter consists of the following data block elements:
|
DBE |
Description |
|---|---|
|
1 |
IDN The IDN contains information such as structure instance (SI), structure element (SE), P, or S parameter. |
|
2 |
Name (up to 240 bytes) |
|
3 |
Attribute The attribute contains information on write protection, decimal places, data type, and display format, procedure command, data length. |
|
4 |
Unit |
|
5 |
Minimum value |
|
6 |
Maximum value |
|
7 |
Operation data Value for operation. The operation data can also contain a list with IDNs for a procedure command. |
Refer to the chapter Configuring Devices via the Service Channel for information on reading and writing parameters.
Procedure commands are parameters which trigger complex processes in the master and in the slaves. Whether a parameter is a procedure command is determined in the attribute of a parameter (data block element 3). Both S parameters and P parameters can be procedure commands.
Procedure commands are executed via the service channel.
Typical examples of procedure commands include:
oS-0-0099 (Reset class 1 diagnostic): If this procedure command is received by a sub-device via the service channel, the diagnostics events with the class error (C1D) are deleted if the cause of the error no longer persists.
oS-0-0127 (CP3 transition verification):The master uses this procedure command to instruct the slave to verify that the parameters required for communication phase CP3 have been transferred.
oS-0-0128 (CP4 transition verification):The master uses this procedure command to instruct the slave to verify that the parameters required for communication phase CP4 have been transferred.
oS-0-0262 (Load defaults): This procedure command instructs a device to load its default parameter values. The extent of the affected parameters as well es the values are defined by the vendor of the device.
Refer to the chapter Configuring Devices via the Service Channel for information on executing procedure command.
