Horner APG SmartStack I/O HE-THM100 - Manual (Page 5)

MAN0237-09 10 NOV 2006 PAGE 5
THM000/100
This Data Sheet is published individually & also as a part of the SmartStack Supplement (SUP0246-05).
Information is subject to change without notice. SmartStack is a trademark of Horner APG, LLC.
5 INSTALLATION / SAFETY
Warning: Remove power from the OCS controller, CAN port, and any peripheral equipment
connected to this local system before adding or replacing this or any module.
1) All applicable codes and standards should be followed in the installation of this product.
2) Shielded, twisted-pair wiring should be used for best performance.
3) Shields may be terminated at the module terminal strip
4) In severe applications, shields should be tied directly to the ground block within the panel.
5) Ungrounded thermocouple sensors are preferred due to their isolated electrical
characteristics
6) Interposing terminal strips between the sensor and the module can cause errors due to cold
junction effect.
7) If Interposing terminal strips must be used, use specially constructed terminal blocks which
match the material characteristics of the thermocouple sensor.
8) Use the following wire type or equivalent: Omega TT-J-20-TWSH for thermocouple input and
Belden 8441 for mV input.
9) Horner thermocouple input modules use a high impedance differential circuit to support the
use of grounded or ungrounded thermocouples. For grounded thermocouples, the specified
Common Mode Range allows for ground potential differences between the machine ground
and the PLC ground within that range. For ungrounded or floating thermocouples the high
impedance inputs are subject to common mode noise pickup. For noisy environments it is
recommended that one side of all ungrounded thermocouples be grounded near the PLC.
This does not affect open thermocouple detection or measurement accuracy and reduces the
effect of common mode noise if present. This PLC side ground connection must not be used
with grounded thermocouples or accuracy will be affected. Any thermocouple should be
grounded in one place at most.
For detailed installation and a handy checklist that covers panel box layout requirements and minimum
clearances, refer to the hardware manual of the controller you are using. (See the Additional
References section in this document.)