Agilent 33120A User's Guide

Chapter 4 Remote Interface ReferenceThe SCPI Status RegistersThe SCPI Status RegistersThe function generator uses the Status Byte register group and theStandard Event register group to record various instrument conditions.A diagram of the SCPI status system is shown on the next page.An example program is included in chapter 6, “Application Programs,”which shows the use of the status registers. You may find it useful torefer to the program after reading the following section in this chapter.What is an Event Register?An event register is a read-only register that reports defined conditionswithin the function generator. Bits in an event register are latched.When an event bit is set, subsequent state changes are ignored. Bits inan event register are automatically cleared by a query of that registeror by sending the *CLS (clear status) command. The *RST (reset)command or device clear will not clear bits in an event register.Querying an event register returns a decimal value which correspondsto the binary-weighted sum of all bits set in the register.4What is an Enable Register?An enable register defines which bits in the corresponding event registerare logically ORed together to form a single summary bit. You can readfrom, and write, to an enable register. Querying an enable register will notclear it. The *CLS (clear status) command does not clear enableregisters but it does clear the bits in the event registers. To enable bitsin an enable register, you must write a decimal value which correspondsto the binary-weighted sum of the bits you wish to enable in the register.201