Discontinued – Max Machinery 286-300 SERIES TRANSMITTERS User Manual

Page 6

Outputs, Options and Indicators

Connections:

The interconnect drawing number 181-000-250 at the end of this manual provides detailed
information on interfacing to Max signal conditioners and indicators.

Output Protection:

Voltage should not be applied to any output (terminals 4, 5, and 6). If a low voltage, 5V or less, is

accidentally applied to an output, resistors and diodes will protect the circuitry. Higher voltages will
destroy the resistors and/or diodes.

Grounding:

S1-1: This switch, (labeled GND) connects Common and Case directly together.
S1-2: This switch, (labeled FILTER) connects Common and Case through two back-to-back 15 uF
capacitors.

By using either S1-1 or S1-2, the effects of electrical noise on the transmitter can be reduced. If the
system is not grounded at the indicator or if the flowmeter is not physically grounded through its
plumbing, use S1-1. If the system is grounded at the indicator, use S1-2. This allows electrical
noise between the case and the transmitter circuitry to be reduced without causing ground loop
problems. To activate either switch, depress the side that is numbered on the switch (and labeled
‘GND’ or ‘FILTER’ on the printed circuit board).

Meter Selection:

S4-1: Depress side that corresponds to meter type. The 210 setting is for Max Series 210 Piston
Flow Meters, and 220/240 is for Max Series 220 Gear and 240 Helix meters.

When used with Max Series 210 Piston Flow Meters, the Model 286 will compensate for the non-
constant rotational velocity of the crankshaft, yielding a steady output frequency at a constant flow
rate. If this switch is placed in the wrong position (for either a 210 or 220/240 meter), the output
frequency will oscillate 20% about its nominal value, four cycles per revolution.

Two-Phase or Square Wave Select:

S4-2: Depress side that corresponds to desired output. ‘2PH’ gives a 2-phase quadrature output
with the two phases separated by 90° (Ph A on Terminal 5 and Ph B on Terminal 6). The ‘COMB
OUT’ setting gives a single square wave output that combines the information in the two phases into
a single output of double the frequency (Combined Output on Terminal 4, Direction on Terminal 6).
If S4-2 is set wrong, an unexpected output signal will result since the same output circuitry is used
for the two distinct output options (see chart below).

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Options & Status Indicators

Outputs, Options & Indicators

Connector

Terminal(s)

S4-2 = 'COMB OUT'

(combined output)

S4-2 = '2Ph'

(2-phase output)

4,5

Pulse Output

Phase A

Direction

Phase B

Terminal Output Signals vs. S4-2 Setting

Discontinued