11.23 Contact Outputs
119
The 1133A must be configured in advance to specify the events being recognized and actions
to be taken.
To maximize usage of flash memory, it is important to distinguish registered quantities from
event log data. The amount of memory needed to record a certain number of registered items for
a certain period can be determined exactly, whereas the amount of memory required to log events
depends on the number and type of events, and the number of items to be recorded for each type.
Since the number and type of events cannot be known a priori, the amount of memory required
also cannot be stated with certainty. The 1133A handles this by allocating sufficient memory as
required for the registered quantities over the specified period of time, and then making whatever
memory is left available for event logging. To deal with low register or event memory conditions,
the 1133A can be configured to initiate an auto-dial call or contact closure when the condition is
met. Memory is allocated in 64-kbyte blocks, which is the block size of the flash memory.
Flash memory must be erased in blocks, and data cannot be over-written until its block is
completely erased. Therefore, the normal process will be to first read out the desired data, and
then erase the blocks, making them available for re-use. All blocks of data are password-protected,
having two levels of security from separate permissions: one to access the data, and a second to
clear it from memory. This means that registered data and event data each have their own sets of
permissions. This would normally be used to separate billing data from operational data.
In addition to the password security, the flash memory is located on a separate module, mounted
internally to the 1133A. In the event of a failure or sabotage to the instrument itself, the memory
module may be removed and read on a separate 1133A mainframe, preventing the loss of critical
billing information and other data.
11.23
Contact Outputs
Four contact outputs may be used to report events recognized by the 1133A, or they may be
controlled remotely, by command.
They may also be operated on a schedule, which may be
downloaded for up to 30 days in advance. In addition to reporting events, these contacts may
be used to synchronize external equipment or to operate load-control switchgear.
11.24
Event Inputs
Four external event inputs are also provided. These are optically isolated and accept dc signals at
levels from 24 to 240 volts (an internal modification will allow 5 volt logic-level inputs). Application
of a signal to one of these inputs will be time-tagged to one microsecond resolution. Resultant
actions from an event input are described above under triggering using event inputs, Section 8.4.
11.25
Serial Channels
Two standard serial channels can be configured at the time of order with RS-232 or RS-485 drivers,
or with a V.34bis 33.6k modem. Each channel can have access to all functions of the 1133A.
Alternatively, certain functions (such as the ability to clear the revenue registers) may be enabled
or disabled independently. Each serial channel has a RJ-11 (6-position) modular connector useful
for connecting with a standard phone cable. Use a RJ-11 to DB-9F adapter at the end of the phone
