Relay Connection - Macurco DVP-120 User Instructions

Topology
An RS485-MODBUS configuration without repeater has one trunk cable, along which devices are connected, directly (daisy chaining)
or by short derivation cables. The trunk cable, also named "Bus", can be long. Its two ends must be connected on Line Terminations.
(see Line Termination - End of Line Resistor section). The use of repeaters between several RS485-MODBUS is also possible.
Length
The end to end length of the trunk cable must be limited. The maximum length depends on the baud rate, the cable (Gauge,
Capacitance or Characteristic Impedance), the number of loads on the daisy chain, and the network configuration (2-wire). For a
maximum 9600 Baud Rate and AWG26 (or wider) gauge, the maximum length is 1000m 3281ft. The derivations must be short, never
more than 20m 65.5ft. If a multi-port tap is used with n derivations, each one must respect a maximum length of 40m 131ft divided by
n.
Grounding
The Common circuit (COM) must be connected directly to protective ground, preferably at one point only for the entire bus.
Power Wire
All field wiring is completed via modular connectors (provided). After wiring, simply plug the modular connectors into the matching
connectors on the MRS-485. The power connections to the remote mounted detectors should be size AWG18 (minimum) for short
runs. Since Macurco detectors are rated for operation between 12 and 24 VDC or VAC, the voltage drop between the power supply
and the MRS-485 should not be an issue if the recommended power wire gauge guidelines below are followed. The terminals will
accept wire from 16 to 28 AWG. To install a wire, strip back approximately 0.25 in. (6 mm) of insulation, and insert the bare wire into
the terminal. Tighten the screw clamp and ensure that the wire cannot be easily pulled from the connector.
Maximum Run Length
Wire gauge (feet) (meters)
18 500
16 800
14 1250
2.5

Relay Connection

All poles of the three relays are available at the modular connector R1 R2 R3 (see Figure 2- for details). R1 R2 R3 is a 9-position
variant of the high voltage modular connector used for power input. Each terminal can accommodate a wire size 12 to 24 AWG.
152
244
381
Figure 2-6 Relay Connector
10