Arroyo Instruments TECSource 5305, User Manual

Page: 30 / 44

Page 30 · 5300 Series TECSource User’s Manual
Resistive Heaters and Heat/Cool Only Modes
The
TECSource supports temperature control using resistive heaters instead of
Peltier coolers. With resistive heaters, cooling is obviously not possible, and the
TECSource must be configured to not attempt to cool the output, or a run-away
condition will occur when the cooling current actually causes additional heating.
If your application requires, you can also configure the
TECSource to operate in
a cool-only mode. This is only possible with Peltier coolers, as resistive heaters
will heat regardless of the direction of current..
To change the cooling mode, adjust the
H/C Mode setting to Heat/Cool , Heat
Only , or Cool Only , as appropriate.
Gain Control and the PID Loop
The
TECSource supports a fully configurable PID loop, allowing full
customization of the PID control parameters. To simplify control, eight standard
gain settings are also defined, and many applications can achieve acceptable
performance with these predefined gain settings, eliminating the need to
understand and adjust the PID loop.
The predefined gains are numbered
1 through 300 , and set using the Gain
menu setting. Increasing the gain value will increase the speed of the control
loop. For full access to the PID parameters, change the
Gain setting to PID , and
the individual P, I, and D values will be available as settings in the menu.
The PID parameters function within a mathematical formula as described below:
PID Formula:

  
dt
d
D dt I P Output



* * *
Where

is the error in the system, expressed as:

= Target - Actual
The controller can calculate ideal PID values using the AutoTune function,
discussed in detail in the next section.
To manually adjust the PID, start by changing the I and D values to zero, and
adjust the P value so that it reaches the set point as quickly as possible without
overshooting the set point an unacceptable amount. Gradually increase the I