Figure 2.20—tb50 watchdog timer output 34, Figure 2.21—tb18 watchdog timer output 34 – Watlow Series D8 User Manual
Page 52
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
+
-