Figure 2.20—tb50 watchdog timer output 34, Figure 2.21—tb18 watchdog timer output 34 – Watlow Series D8 User Manual

Page 52

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Chapter 2: Installation

Series D8 User’s Guide

34

Watlow Anafaze

Doc. 0600-3120-2000

Figure 2.19 Output Connections Using

External Power Supply

CPU Watchdog Timer

The CPU watchdog timer constantly monitors the micropro-

cessor. It is a sink output located on TB50 terminal 6 or TB18

terminal 3. The output can be connected to an external circuit

or device to monitor whether the controller is powered and op-

erational. The output is on (low) when the microprocessor is

operating; when it stops operating, the output goes off (high).
Figure 2.20 and Figure 2.21 show the recommended circuit

for the watchdog timer output for the TB50 and the TB18.

Figure 2.20 TB50 Watchdog Timer Output

Figure 2.21 TB18 Watchdog Timer Output

Heat Output

Cool Output

Alarm Output

Common

+

-

SSR

TB50 or TB18

- PS +

+

-

SSR

+

-

SSR

SSR

+ 5 Vdc

Watchdog Timer

(Terminal 1)

(Terminal 6)

TB50

+

-

SSR

+ 5 Vdc

Watchdog Timer

(Terminal 1)

(Terminal 3)

TB18

+

-