Watlow CLS200 - Manual (Page 55)

CLS200 Series User’s Guide Chapter 2: Installation
Doc.# 0600-3050-2000 Watlow Anafaze 39
off. Most features that use the digital inputs can be user-
configured to activate when an input is either on or off.
In the off state, internal 10 k resistors pull the digital in-
puts high to 5V
Î (dc) with respect to the controller com-
mon.
Table 2.4 Digital Inputs States and Values
Stored in the Controller
External Switching Devices
To ensure that the inputs are reliably switched, use a
switching device with the appropriate impedances in the on
and off states and do not connect the inputs to external
power sources.
When off, the swiching device must provide an impedance
of at least 11 k
Ω
to ensure that the voltage will rise to
greater than 3.7V Î (dc). When on, the switch must provide
not more than 1 k Ω impedance to ensure the voltage drops
below 1.3V Î (dc).
To install a switch as a digital input, connect one lead to the
common terminal on the TB50 (terminals 3 and 4) or TB18
(terminal 2). Connect the other lead to the desired digital
input terminal on the TB50 (terminals 43 to 50) or TB18
(terminals 16 to 18).
Functions Activated by Digital Inputs
Use digital inputs to activate the following functions:
• Load a job that is stored in controller memory. See Job
Select Digital Inputs on page 76.
• Change all loops to manual mode at specified output
levels. See Output Override Digital Input on page 77.
• Enable thermocouple short detection. See Process
Power Digital Input on page 79.
• Restore control automatically after a failed sensor has
been repaired. See Restore PID Digital Input on page 92.
Figure 2.27 Wiring Digital Inputs
State Value Description
Off High Open circuit
On Low
Digital Input connected to
controller common
External
Switching
Device
TB50
Input
Control Com