To Next Page

To Previous Page

1/7/2021 PDF Export

https://docs.johnsoncontrols.com/bas/internal/api/webapp/print/b4118696-0b8a-4733-98fb-fdd04b065b15 32/60

Table 1. Voltage Table

Voltage

Communication

State Meaning Acceptable Range

Bias Voltage Either Idle or

Active

Communication

The + to COM

Reading, - to COM

or + to -. Typically

used such as + is

biased to com, -,

etc. It is the

voltage applied to

the bus by the EOL

termination on the

controller to

establish a

properly biased

bus.

See notes below for

acceptable ranges based

on active or idle

communication states.

Idle Voltage Idle The term idle

voltage could be

referring to + to

COM, - to COM or

the + to –

(differential)

Reading. What it

really means is no

communication is

occurring at the

time of the

reading.

Typically near 2.7 (+ to

com) -2.3 VDC (- to com)

with a differential (+ to -)

of 0.4VDC. Can vary with

wire length & bus load but

should not be lower than

~0.2VDC differential or

higher than ~0.9VDC

differential.

Idle Differential

Voltage

Idle This is typically

referring to the +

to – voltage

reading without

communication.

~0.2 to ~0.9 VDC

Communication

Voltage

Active The term

communication

voltage could be

referring to + to

COM, - to COM or

the + to – Reading.

Communication is

occurring at the

time of the

reading.

See Bit Voltage and

Differential Voltage below.

Brand	Johnson Controls
Model	MS-FIT100-0
Category	Tools
Language	English

Johnson Controls MS-FIT100-0 User Manual

Table of Contents

Questions and Answers:

Johnson Controls MS-FIT100-0 Specifications