7-12 Inputs, Outputs, Timers, and Other Control Logic Date Code 20001006
SEL-351 Instruction Manual
Remote Bit Application Ideas
With SELOGIC Control Equations, the remote bits can be used in applications similar to those that
local bits are used in (see preceding local control switch discussion).
Also, remote bits can be used much as optoisolated inputs are used in operating latch control
switches (see discussion following Figure 7.16). Pulse (momentarily operate) the remote bits for
this application.
Remote Bit States Not Retained When Power is Lost
The states of the remote bits (Relay Word bits RB1 through RB8) are not retained if power to the
relay is lost and then restored. The remote control switches always come back in the OFF position
(corresponding remote bit is deasserted to logical 0) when power is restored to the relay.
Remote Bit States Retained When Settings Changed or Active Setting Group Changed
The state of each remote bit (Relay Word bits RB1 through RB8) is retained if relay settings are
changed (for the active setting group or one of the other setting groups) or the active setting group
is changed. If a remote control switch is in the ON position (corresponding remote bit is asserted
to logical 1) before a setting change or an active setting group change, it comes back in the ON
position (corresponding remote bit is still asserted to logical 1) after the change. If a remote
control switch is in the OFF position (corresponding remote bit is deasserted to logical 0) before a
settings change or an active setting group change, it comes back in the OFF position
(corresponding remote bit is still deasserted to logical 0) after the change.
If settings are changed for a setting group other than the active setting group, there is no
interruption of the remote bits (the relay is not momentarily disabled).
Details on the Remote Control Switch MOMENTARY Position
This subsection describes remote control switch 3, which is also called remote bit 3 (RB3). All of
the remote bits (RB1 - RB8) operate in the same way.
The CON 3 command and PRB 3 subcommand places the remote control switch 3 into the
MOMENTARY position for one processing interval, regardless of its initial state. Remote control
switch 3 is then placed in the OFF position.
If RB3 is initially at logical 0, pulsing it with the CON 3 command and PRB 3 subcommand will
change RB3 to a logical 1 for one processing interval, and then return it to a logical 0. In this
situation, the /RB3 (rising edge operator) will also assert for one processing interval, followed by
the \RB3 (falling edge operator) one processing interval later.
If RB3 is initially at logical 1 instead, pulsing it with the CON 3 command and PRB 3
subcommand will change RB3 to a logical 0. In this situation, the /RB3 (rising edge operator) will
not assert, but the \RB3 (falling edge operator) will assert for one processing interval.
See CON Command (Control Remote Bit) in Section 10: Serial Port Communications and
Commands.
Courtesy of NationalSwitchgear.com
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