The 3270 attached to a 3790 (Version 7) uses the LU type 2 protocol. You need to give session parameters to TSO/VTAM through a logon mode table entry to properly identify the model number or screen sizes of the device being used. The 3270 operator selects FPID 932 when logging on to the 3790 to activate the 3270 data stream compatibility function. During the logon procedure, the operator is prompted for the application program ID and the logon mode table entry containing the session parameters to be used for that session. The information is transmitted to VTAM® by the Initiate Self request generated by the 3790. If the operator does not supply a logon mode table entry, the 3790 uses the standard logon mode entry name EMU3790.

So that the terminal operator does not have to know what logon mode entry name to supply, create a separate logon mode table for each 3270 model attached to the 3790, and include the default entry name EMU3790 in each table with the correct session parameters for that device.

Use the MODETAB and MODEENT macroinstructions to define the logon mode table and its entry. The PSERVIC operand on the MODEENT macroinstruction carries the model number or screen sizes in row and column form. Following is an example of defining a logon mode entry for a 3270 attached to a 3790 with a screen size of 1920 bytes (Model 2).