D8 Series User’s Guide
Chapter 2: Installation
31
2. Connect the voltmeter’s positive lead to terminal 1 on the TB50 or TB18.
3. Connect the voltmeter’s common lead to the digital output terminal.
4. Use the digital output test in the I/O tests menu to turn the digital output on and off. See Test
Digital Output 1 to 20 on page 132. When the output is off, the output voltage should be less
than 1V. When the output is on, the output voltage should be between 4.75 and 5.25V.
NOTE!
By default, heat outputs are enabled. Only disabled outputs may be turned on
using the manual I/O test. To test heat outputs, set the corresponding loop to manual
mode 100 percent output. See Changing the Control Mode and Output Power on page
66.
Digital Input Test
Use the following procedure to test digital inputs before connecting to field devices:
1. Disconnect any system wiring from the input to be tested.
2. Go to the
Digital inputs
test in the
I/O tests
menu. This test shows whether the digital inputs
are off (open) or on (closed).
3. Attach a wire to the terminal of the digital input you want to test. See See Table 2.7 – TB18
Connections on page 39. or See Table 2.8 —TB50 Connections on page 40. for
connections.
a. When the wire is connected only to the digital input terminal, the digital input test should
show that the input is off (open).
b. When you connect the other end of the wire to the controller common (TB50 terminal 3 or
TB18 terminal 2), the digital input test should show that the input is on (closed).
Sensor Wiring
This section describes how to properly connect thermocouples, RTDs, current and voltage inputs to
the controller. The controller can accept any mix of available input types. Some input types require
that special scaling resistors be installed (done by Watlow before the controller is delivered).
Sensors connect via a DB25 cable to J1 on units with the mass termination option for analog
inputs and at screw terminals TB1 on units with at the screw termination option. The tables below
list the connections for each sensor and the illustrations that follow show how to connect the various
sensor types.
CAUTION!
Never run input leads in bundles with high power wires or near other sources
of EMI. This could inductively couple voltage onto the input leads and damage the
controller, or could induce noise and cause poor measurement and control.
