D8 Series User’s Guide
Chapter 7: Troubleshooting and Reconfiguring
148
Figure 7.7
— Battery-Backed RAM Module on the Processor Board
To replace the battery, if desired:
1. Align the contact springs on the battery holder with the contacts on the RAM module.
2. Hook the battery holder flange under the RAM module’s base board.
3. Fit the alignment ribs on the battery holder into the alignment notches in the RAM module’s
base board.
4. Push down and forward and latch the battery holder on the module.
5. To reassemble the unit reverse steps 3 through 7 of the procedure
. However, at step 6 insert the two-board assembly straight in to the carrier
making sure all four arms latch on the boards.
6. Power up the controller.
7. Re-enter the controller settings, if necessary.
Scaling Resistors
Resistors are installed for all inputs on the D8. Inputs with signal ranges between -10 and +60mV
use 0Ω resistors in the RC position only. All other input signals require special input scaling resistors.
NOTE!
Scaling resistors cannot be changed in the field. For input types other than
thermocouples, the controller must be ordered with and factory configured with scaling
resistors.
Input Circuit
The D8 can accept thermocouple, mVDC, VDC, mADC and RTD inputs. Unless ordered with special
inputs the controller accepts only signals within the standard range -10 to 60mVDC.
To accommodate other signals, the input circuit must be modified. When configured for
thermocouple inputs, 0Ω resistors are installed in all RC locations. To accommodate voltage signals
outside the standard range, milliamp current signals or RTDs, resistors are added or replaced to
scale the signals to the standard range.
Figure 7.8 shows the input circuit for one analog input. See Current Inputs on page 149 through
RTD Inputs on page 150 for specific instructions and resistor values for voltage, current and RTD
inputs.
