
System Planning About battery-backup operation
Remote I/O Module (IO-16-485) Mounting and Wiring Instructions
Part Number 11156, Rev 1.3 Updated:August 20, 2014 3
About battery-backup operation
When IO-16-485 modules are powered by JACE platforms with 6-position power/RS-485 connectors, that is,
wired to the PS+, PS-, and BB terminals, they can benefit from “battery backed” protection against system
power events. Note this requires the JACE to have the optional (external) sealed lead acid battery installed—as
the JACE’s internal NiMH battery provides “power blip” backup only for its onboard circuitry, as well as a
“graceful shutdown” of its running station, if a longer power outage occurs.
Note The other “direct attachment type” I/O expansion modules (IO-16, IO-34, using Ndio driver) already
provide this type of “shutdown protection” described above.
An IO-16-485 with battery backup can provide continuous system operation during a power event—essentially
making it a “non event” for both the JACE and the IO-16-485 module. Depending on the capacity of the external
battery(ies), this backup operation can extend over many minutes of AC power loss, and/or over multiple
successive power blips. An IO-16-485 wired this way is often described as “powered by the JACE”, although
during normal operation, sometimes power is actually supplied by the NPB-PWR-UN module attached to, and
powering, the JACE itself (JACE-700, SEC-J-601).
Note this “supplied by JACE” battery-backup operation is not available when using IO-16-485 modules with
JACE-2/3E/6/6E series controllers, that is JACEs without the 6-position power/RS-485 connector. Or, in any
scenarios where IO-16-485 modules must be located many hundreds of feet away from the JACE (cabling
“voltage drop” issues). In these cases, you must locally power those IO-16-485 modules, using one of two
methods:
• Local NPB-PWR-UN attachment to the IO-16-485 module(s). Although convenient, be aware that this
invites power event issues. See “Operation without battery-backup.”
• Third party, battery-backed 12Vdc power supply, wired to the PS+ and PS- terminals of the IO-16-485
module’s 6-position end connector. This is typically recommended, for reasons noted below.
Note that power wiring for all different scenarios is included in this document. See “Wiring Details,” page 10.
Operation without battery-backup
If an IO-16-485 module is powered locally with an NPB-PWR-UN (for example, a JACE-6 series job), and a
momentary AC power loss occurs, note that a number of undesirable things can result, including:
• Load cycling from IO-16-485 relays dropping out, including several seconds lag to first re-establish
communications with the JACE (Nrio driver) before relays can pull in again, as needed.
• Loss of totalized “counts” originating in the IO-16-485.
• History (logging) entries for associated IO points as “down,” as well as Nrio “device down” alarms.
Further, loss of power without battery backup makes an IO firmware upgrade a risky operation. Such an upgrade
is initiated from the “Nrio Device Manager” view (in a station connection to the JACE). If this upgrade process
is interrupted by an IO-16-485 power cycle, the module may be rendered inoperable—and will likely need to be
replaced.
Therefore, consider powering IO-16-485 modules with a battery-backed 12V power supply, as necessary.