Watlow CLS200 - Manual (Page 196)

Chapter 9: Troubleshooting and Reconfiguring CLS200 Series User’s Guide
180 Watlow Anafaze Doc.# 0600-3050-2000
Installing Scaling Resistors
Resistors are installed for all inputs on the CLS200. Inputs
with signal ranges between -10 and +60 mV use 0
Ω resis-
tors in the RC position only. All other input signals require
special input scaling resistors.
CAUTION! Scaling resistors are soldered to the circuit
board. Only qualified technicians should at-
tempt to install or remove these components.
Improper techniques, tools or materials can
result in damage to the controller that is not
covered by the warranty.
CLS204 and CLS208 Input Circuit
The CLS204 and CLS208 can accept differential thermo-
couple, mV
Î (dc), V Î (dc), mA Î (dc) and RTD inputs. Un-
less ordered with special inputs these controller accept only
signals within the standard range -10 to 60mV
Î (dc).
To accommodate other signals, the input circuit must be
modified. When configured for thermocouple inputs, 0
Ω
re-
sistors are installed in all RC locations. To accommodate
voltage signals outside the standard range, milliamp cur-
rent signals or RTDs, resistors are added or replaced to
scale the signals to the standard range. These resistor can
be installed by Watlow Anafaze or by a qualified electronics
technician using scaling resistors supplied by Watlow
Anafaze.
Figure 9.6 shows the input circuit for one differential, ana-
log input. See CLS204 and CLS208 Current Inputs on page
181 through CLS204 and CLS208 RTDs and Thermistors
on page 183 for specific instructions and resistor values for
voltage, current and RTD inputs.
NOTE! When adding your own scaling resistors to
the controller, for voltage and RTD inputs
you will have to carefully remove one of the
RC resistors in order to install the resistor
listed in the table.