The method of data exchange using the unsolicited TSAP is different depending on whether the device has been defined as unsolicited or not.

If the device is not an unsolicited device, one can send or receive data to or from Siemens programmable controllers using the unsolicited TSAP with the ILAN$DEVICE_SPECIFIC routine. Refer to Appendix B for more information.

If the device is defined as unsolicited (by the /UNSOLICITED qualifier in the CREATE DEVICE command), the unsolicited TSAP can be used:

• by the DAS to perform a read operation, an acknowledged write operation or an unacknowledged write operation.
• by the programmable controller to send unsolicited data to the DAS for Siemens H1 Protocol.

All these operations are described in this appendix.

The unsolicited TSAP is defined by specifying the name of the unsolicited TSAP in the /NETADDR definition of the Siemens device.

When the DAS for Siemens H1 Protocol uses the unsolicited TSAP to exchange data with a device defined as unsolicited, it sends for each request a message header, made of 2 longwords, that may be followed by some specific data.

The programmable controller must be programmed to understand this message header, and to cooperate with the DAS for Siemens H1 Protocol.

C.1 Read Operation

For example:

DCM> READ DATA S135/ADDR=ACK:xxxx/FORMAT=ARRAY[10]:WORD

The Siemens sends the following buffer to the programmable controller over the unsolicited TSAP:

Where:

• xxxx is any positive integer value that fits in a longword.
  This value is given by the /ADDR qualifier. It is called the message ID.
• request_id is the identifier for the read request block, as it has been allocated by the DAS for Siemens H1 Protocol.

The message ID "xxxx" may be used by the program in the programmable controller to find out what kind of data is expected by the DAS for Siemens H1 Protocol. The programmable controller must answer by returning the message header sent by the DAS, followed by the requested data:

For example:

DCM> WRITE DATA S135/ADDR=ACK:xxxx/FORMAT=ARRAY[3]:WORD

The Siemens sends the following buffer to the programmable controller over the unsolicited TSAP:

Where:

• xxxx is any positive integer value that fits in a longword.
  This value is given by the /ADDR qualifier. It is called the message ID.
• request_id is the identifier for the write request block, as it has been allocated by the DAS for Siemens H1 Protocol.
• data represents the data sent to the programmable controller.
  Inin our example, it would be a 3 words long buffer.

The message ID "xxxx" may be used by the program in the programmable controller to find out what kind of data has been sent by the DAS for Siemens H1 Protocol. The programmable controller must acknowledge the write request by returning the message header:

For example:

DCM> WRITE DATA S135/ADDR=NAK:xxxx/FORMAT=ARRAY[5]:LONGWORD

The Siemens sends the following buffer to the programmable controller over the unsolicited TSAP:

Where:

• xxxx is any positive integer value that fits in a longword.
  This value is given by the /ADDR qualifier. It is called the message ID.
• data represents the data sent to the programmable controller
  In our example, it would be a 5 longwords long buffer.

When the second longword sent by the DAS for Siemens H1 Protocol is set to 0, the programmable controller must understand that this involves a non acknowledged write operation, and that it has not to return any answer.

The message ID "xxxx" may be used by the program in the programmable controller to find out what kind of data has been sent by the DAS for Siemens H1 Protocol.

C.4 Unsolicited messages

Unsolicited data involves a device sending a physical point to BASEstar Classic device connection management without BASEstar Classic device connection management requesting it. BASEstar Classic device connection management accept unsolicited values from any device, as long as the device is defined as unsolicted and the physical point is defined with unsolicited information.

When the device sends an unsolicited message, it must use the following format:

Where:

• xxxx is any positive integer value that fits in a longword.
• the second longword of the message header must be set to 0.
• data represents the unsolicited data sent by the programmable controller.

When the DAS for Siemens H1 Protocol receives a message on the unsolicited TSAP, it first checks the second longword of this message: if it is zero, the message is unsolicited.

The DAS for Siemens H1 Protocol then checks if a physical point has been defined with an unsolicited ID equal to "xxxx", first longword of the unsolicited message header.

If this is the case, the data part of the unsolicited message is copied into the physical point.

Such a physical point could have been created with following command:

DCM> CREATE PHYP U1/DEV=S135/UNSOLICITED="xxxx" ...