Lathem DDC4-RS-24 - Manual (Page 13)

LTR-GPS Installation and Setup Guide
C H A P T E R 4
Connect Slave Devices
1. Connect a category 3 or 5 cable to the terminal block using a small, flat-blade
screwdriver. Connect one of the four twisted-pairs of the cable to the D+/D-
terminals on the LTR-GPS unit. This provides synchronization commands to the
Lathem slave devices. Connect the other end of the selected pair to the SYNC_IN
D+/D- terminals of a Lathem LTRx-512-series master control (Fig.2) or to
Lathem DDCx Series digital wall clocks (Fig.4). Be sure to maintain consistent
polarity of the D+/D- signals. If the LTR-GPS will be powered by a Lathem
master control within a 200 foot proximity, then connect another twisted-pair to
the terminals marked ‘~’ on both devices (Fig.2).
2. Secure the power and data cables to the LTR-GPS unit using the tie-wraps
(Fig.1). Connect the data cable(s) to Lathem slave time display devices to be
controlled. The twisted-pair data cable can supply data for 31 (max) devices
located within 4,000 feet. Simply daisy-chain the twisted-pair from slave to
slave, maintaining consistent polarity for the D+ / D- signals. A Lathem
SWIFT485+ RS-485 Bus Repeater allows for more than 31 devices or cable
lengths beyond 4,000 feet.
3. Connect the Lathem slave devices using the twisted pair from the RS485 cable
according to the User Manual instructions for each device.
4. If the LTR-GPS will be connected to an LTRx-512 master control that is already
in operation, then the master will not immediately recognize the signal from the
LTR-GPS. It will start recognizing the GPS signal within 15 minutes past
midnight or after power-up. To accelerate the recognition process, the installer
may power-off / power-on the Master by carefully removing the front panel and
toggling the internal power switch, or by briefly disconnecting the Master from its
AC power source. BE CAREFUL: HAZARDOUS VOLTAGES ARE PRESENT.
Page 10