Weidmuller G128 User Manual

Weidmuller Ltd.
10 Spy Court
Markham, ON L3R 5H6
Tel: [phone]
Fax: [phone]

Weidmuller Inc.
821 Southlake Blvd.
Richmond, VA 23236 U.S.A.
Tel: [phone]
Fax: [phone]

ISO 9001 Registered

Electronic Interface Modules

G128 Ultra SlimPak®

Thermocouple Input, Field Configurable
Limit Alarm

• field configurable via DIP switches for different input­output combinations

• provides relay contact closure(s) at a preset
temperature input level

• field configurable input ranges for J, K, T, R, S, E and
B type thermocouples

• setpoints programmable HI or LO and failsafe or non­failsafe

• LED trip and input indicators

• 9 to 30Vdc powered

• CSA approved, UL recognized, CE marked

Description

Diagnostic LEDs

Output

Operation

Dynamic Deadband

The Ultra SlimPak G128 is a DIN rail mount, thermocouple input limit alarm with input terminal cold junction
compensation (cjc), dual setpoints and two contact closure outputs. The field configurable input and alarm
functions offer flexible setpoint capability. There are up to six temperature ranges available for each
thermocouple type to ensure accuracy and maximize setpoint resolution. A bipolar input switch is provided
for temperature ranges below 0°C.
The G128 is configurable as a single or dual setpoint alarm, with HI or LO trips, upscale or downscale
thermocouple burnout detection and failsafe or non-failsafe operation. Also included are adjustable
deadbands (0.25 to 5% of full scale input) for each setpoint and a flexible DC power supply which accepts
any voltage between 9 and 30Vdc.

The G128 is equipped with three front panel LEDs. The first is a dual function LED labeled INPUT. This
green LED indicates DC power and input signal status. Active DC power is indicated by an illuminated LED.
If this LED is off, check line power and wiring connection. If the input signal is more than 110% of the full
scale range, the LED will flash at 8 Hz. Below 0%, the flash rate is 4 Hz.
Two red LED's indicate the relay state for each setpoint. An illuminated red LED indicates the tripped
condition.

The G128 is equipped with two SPDT (form C) relays, rated at 120Vac or 28Vdc at 5 amperes. Each of
these relays is independently controlled by the field configurable set point and deadband.

The field configurable G128 limit alarm setpoints can be configured for HI or LO, failsafe or non-failsafe
operation. Each of the setpoints has a respective HI or LO deadband. In a tripped condition, the setpoint is
exceeded and the appropriate red LED will illuminate. The trip will reset only when the process falls below
the HI deadband or rises above the low deadband (see Figure 1). For proper deadband operation, the HI
setpoint must always be set above the LO setpoint.
In failsafe operation, the relay is energized when the process is below the HI setpoint or above the LO
setpoint (opposite for non-failsafe). In the failsafe mode, a power failure results in an alarm state output.

LSI circuitry in the G128 prevents false trips by repeatedly sampling the input. The input must remain beyond
the setpoint for 100 milliseconds, uninterrupted, to qualify as a valid trip condition. Likewise, the input must
fall outside the deadband and remain there for 100 milliseconds to return the alarm to an untripped
condition. This effectively results in a "dynamic deadband" - based on time- in addition to the normal
deadband.

Table 1
G128 input range
selector - switch settings

Key: n ON

Figure 1

+

Load

Relay

Conta cts

Diode

(optio nal)

Figure 2: DC Inductive Loads

Relay

Conta cts

Figure 3: AC Inductive Loads

47 ohm

1/2W

47 ohm

1/2W

Load

MOV

0.1uF

0.1uF

Film

Film

Power

Power

-