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Chapter 5, Advanced Operations

Status Reporting

Transition Filters are read-write. Transition Filters are unaffected by a *C LS

(clear status) command or queries. The Transitions Filters are set to pass positive

transitions (PTR) at power on and after receiving the *RST (reset) command (all

16 bits of the PTR register set to 1 and all 16 bits of the NTR register set to 0).

Event Register. The Event Register captures bit-state transitions in the Condition

Register as defined by the Transition Filters. Each bit in the Event Register

corresponds to a bit in the Condition Register, or if there is no Condition Regi st er /

Transition Filter combination, each bit corresponds to a specific condition in the

Test Set. Bits in the Event Register are latch ed, and, o nce s et, t hey remain s et u ntil

cleared by a query of the Event Register or a *CLS (clear status) command. This

guarantees that the application can’t miss a bit-state transition in the Condition

Register. There is no buffering; so while an event bit is set, subsequent transitions

in the Condition Register corresponding to that bit are ignored. Event Registers

are read-only. Event Registers in the Test Set are either 8 or 16 bits long and may

contain unused bits. All unused bits return a zero value when read.

Event Enable Register. The Event Enable Register defines which bits in the Event

Register will be used to generate the Summary Message. Each bit in the Enable

Register has a corresponding bit in the Event Register. The Test Set logically

ANDs corresponding bits in the Event and Enable registers and then performs an

inclusive OR on all the resulting bits to generate the Summary Message. By using

the enable bits the application program can direct the Test Set to set the Summary

Message to the 1 or TRUE state for a single event or an inclusive OR of any group

of events. Enable Registers are read-write. Enable Registers in the Test Set are

either 8 or 16 bits long and may contain unused bits which correspond to unused

bits in the associated Event Register. All unused bits return a zero val ue when read

and are ignored when written to. Enable Registers are unaffected by a *CLS (clear

status) command or queries.

Summary Message Bit. The Summary Message is a single-bit message which

indicates whether or not one or more of the enabled events have occurred since the

last reading or clearing of the Event Register. The Test Set logically ANDs

corresponding bits in the Event and Enable registers and then performs an

inclusive OR on all the resulting bits to generate the Summary Message. By use of

the enable bits, the application program can direct th e Test Set to set the Summary