D8 Series User’s Guide
Chapter 8: Specifications
159
Table 8.12
– Digital Inputs
Number
With TB50: 8
With TB18: 3
Function
Selectable for output override or remote job selection
Input Voltage Protection
Diodes to supply and common. Source must limit
current to 10mA for override conditions
Voltage Levels
<1.3V = Low
>3.7V = High (TTL)
5V maximum, 0V minimum
Maximum Switch Resistance to
Pull Input Low
1.7k
Ω
Minimum Switch Off Resistance
1.4k
Ω
Response Time
50ms (AC line frequency set to 60Hz)
60ms (AC line frequency set to 50Hz)
Outputs
The controller directly accommodates switched dc and open-collector outputs only. These outputs
can be used to control a wide variety of loads. They are typically used to control solid-state relays
or other power switching devices which, in turn, control devices such as heaters. They may also be
used to signal another device of an alarm condition in the controller.
An open-collector CPU watchdog output is also provided so that an external device can monitor the
CPU state.
Analog Outputs
Contact your supplier or Watlow for more information on these accessory products. Contact your
supplier or Watlow for more information on these accessory products.
Digital Outputs
Table 8.13
– Digital Outputs Control / Alarm
Number
20 with TB50 option or 11 with TB18 option
Operation
Open collector output; ON state sinks to logic common
Function
1 Global alarm output
1 CPU watchdog output
Balance selectable as closed-loop control or alarms
Number of Control Outputs per
PID Loop
2 (maximum)
Control Output Types
Time proportioning, distributed zero crossing, Serial DAC or on/off.
All independently selectable for each output. Heat and cool control
outputs can be individually disabled for use as alarm outputs
Time Proportioning Cycle Time
1 to 255 seconds, programmable for each output
Control Action
Reverse (heat) or direct (cool), independently selectable for each output
Off State Leakage Current
<0.01mA to dc common
Maximum Current
60mA for each output. 5V power supply (from the processor module)
can supply up to 350mA total to all outputs
Maximum Voltage Switched
24VDC