Installation   
  EST3 Installation and Service Manual 
5.28
The remote programs, ACDB and KDC, use passwords defined 
during 3-SDU programming to gain access to the 3-MODCOM. 
At the start of the downloading process, a connection is 
established between the modem portion of the 3-MODCOM 
module and the ACDB or KDC program. Connection is over the 
telephone network. 
The 3-MODCOM module receives data and transfers it to the 
CPU. The data is then routed via the 3-SAC to the CRC and 
KPDISP modules on the SAC bus. The data is stored in the 
nonvolatile flash memory chips of these devices.  
Monitoring and diagnostics 
Each line has a voltage monitor for detecting loss of telephone 
line during on-hook condition, and a current monitor for 
detecting the loss of telephone line and telephone line usage 
during off-hook conditions. Optical coupler circuits are used for 
these monitors. 
Two red LEDs (DS1 and DS2) annunciate line ringing, in use, 
and fault conditions. States and explanations for DS1 and DS2 
are given in the “Service and troubleshooting” chapter. 
Equipment 
3-MODCOM – Modem Communicator 
The 3-MODCOM connects the EST3 system to the switched 
telephone network. The 3-MODCOM module is a single rail 
module with two eight-position modular jacks for connecting 
two loop-start lines. The 3-MODCOM module provides a 
control / display layer and space for a future expansion insert 
card. 
The 3-MODCOM can support 255 accounts. It can communicate 
with 80 receivers in any of the following protocols: 
• Contact ID 
• SIA DCS 
•  SIA P2 (3/1 Pulse Format) 
•  SIA P3 (4/2 Pulse Format) 
The 3-MODCOM is supplied with two seven-foot cables (P/N 
360137). These are eight-conductor, flat telephone cables, with 
eight-position modular plugs on both ends. One end of the cable 
plugs into the 3-MODCOM. The other end plugs into an RJ-31X 
jack. 
You must obtain the RJ-31X jack locally, and wire it to the 
telephone lines as indicated on the 3-MODCOM installation 
sheet.