Model 6517B Electrometer Reference Manual Section 13: Status structure
6517B-901-01 Rev. C / August 2015 13-9
Transition filters
As shown in the illustrations, all status register sets, except the standard event status register set,
have a transition filter. A transition filter is made up of two registers that are programmed by the user.
It is used to specify which transition (0 to 1, or 1 to 0) in the condition register sets the corresponding
bit in the event register.
A filter can be programmed for positive transitions (PTR), negative transitions (NTR) or both. When
an event is programmed for a positive transition, the bit in the event register sets when the
corresponding bit in the condition register changes for 0 to 1. Conversely, when programmed for a
negative transition, the bit in the event register sets when the corresponding bit in the condition
register changes from 1 to 0.
The :PTR and :NTR commands in the Status Subsystem are used to set or clear the individual bits
of the transition filter registers, while the :PTR? and :NTR? query commands are used to read the
registers (see SCPI command reference (on page 14-1) for details). Reading a transition filter register
does not affect its bit pattern.
The following operations set (1) all bits of all PTR registers and clear (0) all bits of all NTR registers:
ï‚· Cycling power
ï‚· Sending :STATus:PRESet
Event registers
As shown in the illustrations, each status register set has an event register. An event register is a
latched, read-only register whose bits are set by the corresponding condition register and transition
filter. Once a bit in an event register is set, it remains set (latched) until the register is cleared by a
specific clearing operation. The bits of an event register are logically ANDed with the bits of the
corresponding enable register and applied to an OR gate. The output of the OR gate is applied to
another register set or to the status byte register.
The *ESR? Common Command is used to read the Standard event register (see Common
commands (on page 12-1)). All other event registers are read using the [:EVENT]? query
commands in the STATus Subsystem (see SCPI command reference (on page 14-1)).
An event register is cleared when it is read. The following operations clear all event registers:
ï‚· Cycling power
ï‚· Sending *CLS
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