Johnson Controls 300 Series Manual page 98

98 Network Control Module 300 Series Technical Bulletin
Replacing the Battery Pack
To replace the battery pack:
1. Remove the battery/Dynamic Random Access Memory (DRAM)
cover.
2. Disconnect the battery and firmly pull on the battery cable. (This
dislodges the battery pack from the cover.)
3. Place the new battery pack in the cover so that the fastener material
is aligned.
4. Press the battery pack down firmly.
5. Reconnect the cable and press the battery connector against the
small patch of fastener material on the side of the cover.
6. Replace the cover.
The battery pack (Figure 1: Callout 11) is secured to a cover and fits
over the SIMMs. It automatically recharges from the NCM and
maintains the operating system and databases in RAM for up to a
72-hour power failure. (See Table 6 for backup times according to
memory configuration.)
The NCM arrives from the factory with the battery pack unconnected.
Connect the battery last when installing the NCM.
Battery Power Fail Test
Refer to the NCM Maintenance Flowcharts section of this document
for instructions on performing the battery Power Fail test.
Test for Recoverability
A critical aspect of a Metasys network is for NCMs to recover from
expected or unexpected Power Fail. A significant aspect of NCM
maintenance is to perform routine Power Fail tests. There are certain
conditions, which prevent NCMs from recovering from a Power Fail.
Bad batteries can cause a DRAM memory parity error during the
power up portion of a Power Fail. Also, if a job has not been retrofitted
with the latest SIMM (NCM300) or flash code, a Power Fail can cause
NOVRAM corruption on power up.
Routine Power Fails could possibly catch the power up problem prior
to experiencing an actual Power Fail and causing the NCM to be
nonfunctioning.
Use the Power Fail Test Worksheet (PFTWS) to test each NCM for
recoverability.