AM3270/TR3271 Reference Manual

Details of the CRT Protocol

AM3270 Subdevice Protocols

4–16 086705 Tandem Computers Incorporated

SETMODE 59 Operation SETMODE 59 returns the actual count of bytes read as a result of a CONTROL 22

(two-step READ) completion. The format is:

CALL SETMODE (filenumber, 59, , , params);

filenumber

INT:value, the file number returned by the OPEN for the subdevice.

INT:value, the SETMODE number for obtaining the actual count of the bytes read.

params

INT:ref:2, must be provided and returns:

params[0] actual number of bytes read.

params[1] 0 (zero).

Note that the parameter positions normally used for param1 and param2 are not

used and parameters must not be provided. If they are, an Error 2 (invalid

operation attempted) will be returned to the caller. Error 26 will be returned if the

subdevice has no outstanding two-step READs completed or if the SETMODE

requestor is not the two-step READ requester.

SETMODE 59 Example

The following is a functional example of the application request sequence using a two-

step READ and a SETMODE 59:

CALL OPEN (T^NAME,T1,FLAGS); open the subdevice.

CALL CONTROL (T1,22,500); post a 500-byte READ to T1

CALL AWAITIO (T1, ... ); and wait for completion.

CALL SETMODE (T1,59,,,PARAMS); read has completed, get

. the actual size.

CALL READ(T1,BUFFER,PARAMS[0]); .I/O has completed using

. the actual message size

. rather than 500.

WRITE Request A WRITE request causes polling to be halted. A select operation is initiated for the

subdevice. If the select is properly acknowledged by the device, AM3270 adds the

communication control characters to the text to be written and writes it to the device.

Completion of the physical write to the device causes the WRITE request to be

completed.