Electronic Bypass Option Overview

Controller Board

The Controller board is the foundation of the SED2 Electronic Bypass Option. It controls communications to and from the SED2, keypad, isolated digital inputs, relay/digital outputs, and contactors (Figure 3).

SED2 INTERFACE

Supports two SED2 non-isolated, digital relay outputs and three SED2 digital inputs. The maximum current draw for a relay output is 2 mA and the voltage between the digital output source and return lines is 24V. The Controller board provides unregulated, non-isolated 24V to power the SED2 digital inputs.

BASIC SANITY TEST INDICATOR

Provides indication of initialization and normal operation.

KEYPAD INTERFACE

Supports inputs and outputs from the Electronic Bypass Option keypad. The keypad provides user interface indicators and push buttons.

FACTORY USE ONLY

Connector J8 is for factory use only.

DIGITAL INPUTS

Supports six isolated digital inputs for customer use. The inputs require a contact closure capable of providing a low impedance path at currents less than 20 mA.

DIGITAL RELAY OUTPUTS

Supports six digital relay outputs for customer use. Each relay has a maximum rating of 2A at 120 Vac.

OVERRIDE JUMPER

DIP SWITCHES

The Controller board DIP switches enable/disable

the Electronic Bypass Option features.

J4

CONTROLLER

BOARD

 

 

 

 

J3

MCU

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

J8

 

 

 

 

 

 

ON

 

 

OFF

 

 

SW1

 

 

J2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

J1

TRANSFORMER

F1

 

J6

J7

J5

 

 

 

 

 

CONTACTOR POWER

CONTROLS

ON

 

5

 

OPTIONS 3 4

 

2

 

1

ON

1 2 3 4 5

OFF

Not used, factory test selector switch #2; leave this switch OFF.

Not used, factory test selector switch #1; leave this switch OFF.

Interlock selector switch; requires SED2 programming.

Automatic Bypass selector switch; requires SED2 programming.

Essential Services selector switch.

VFD0095R1

SW1

When the switch is ON the option is enabled; when the switch is OFF the option is disabled.

Figure 3. Controller Board Inputs and Outputs.

Siemens Building Technologies, Inc.

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Siemens 125-3208 operating instructions Controller Board Inputs and Outputs