Optional Rs Communication Connections; Selecting The External Loop Resistor; Rs-232C / Rs-485 Connections - Honeywell Enraf 854 ATG Installation Manual

When the voltage exceeds 30 Vdc,
an additional resistor is required.
The permitted operational areas are
shown in figure 9.
Operational area 1 represents the area of
operation without the need of an external
loop resistance.
Operational area 2 shows the area where
a resistance is required.
The power rating of the external resistor
depends on the value of the resistor.
We recommend 1 W / kΩ

Optional RS communication connections

For the cable connections of the mains and the alarm contacts, refer to previous section.
RS-232C : Cable requirements: maximum length 15 metres (50 ft); twisted and shielded.
RS-485 : Cable requirements: maximum length 1200 metres (3900 ft); twisted and shielded.
Figure 10

RS-232C / Rs-485 connections

Keep the RS-232C / RS-485 lines as short as possible.
Installation guide 854 ATG
Figure 9

Selecting the external loop resistor

Caution
Electrical installation
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