Tektronix 071-0590-00 Service Request Enable, Service Request SRQ, Standard Event Status Register

Using GPIB, RS-232

Service Request Enable

Different conditions for a service request can be individually enabled. The Service Request Enable byte contains the enabling bits for the status byte. For a service request to occur, either the TSB, MAV or ESB bit must be enabled. Each time the GB1400 is powered on, this byte is RESET so that no bits are enabled. The bit definition is the same as the status byte, except bit 7 is undefined.

Service Request (SRQ)

The status byte enables the creation of a service request. Whenever a condition requiring service from the controller occurs and is enabled, the SRQ line is set. It is reset after the controller finishes a serial poll of the GB1400 receiver, or when all of the enabled service request conditions have stopped.

Standard Event Status Register

The ESB bit is the summary of the Standard Event Status Register. This byte has an enabling byte similar to the Status Byte. Individual bits within the Standard Event Status Register represent the different possible causes of a Standard Event. The bit definitions for the Standard Event Status Register are as follows:

Bit 1	Operation	Only set following an *OPC command
	Complete
Bit 2	Request Control	Not Used
Bit 3	Query Error	Set under the following conditions:
		∙ when output has been requested from the
		GB1400 and none is available
		∙ when a command is sent to the GB1400 and
		GB1400 still has a message available
		∙ when output has been requested from the
		GB1400 and an unterminated command has
		been set to the GB1400
Bit 4	Device	Set under the following conditions:
	Dependent Error	∙ when input data is lost over the interface
		∙ when the input buffer overflows due to a too-long
		command line without a terminator
Bit 5	Execution Error	Set under the following conditions:
		when a command parameter is out of range
		when the command has too many or too few
		parameters
		when the command cannot be properly executed
		due to a device condition
Bit 6	Command Error	Set whenever the GB1400 receives an unrecognized
		command, or invalid GPIB command
Bit 7	User Request	Not used
Bit 8	Power On	Set whenever the GB1400 is powered on

D-4 GB1400 User Manual