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CHAPTER 6 INSTALLATION AND WIRING
6
6.6 Wiring of Terminal Block and External Devices
(c) Precautions for external wiring
To obtain the maximum performance from the functions of the A/D converter module and improve the system
reliability, an external wiring with high durability against noise is required. Precautions for external wiring are as
follows:
• Use separate cables for the AC control circuit and the external input signals of the A/D converter module to
avoid the influence of the AC side surges or induction.
• Do not install cables together with the main circuit lines, high voltage lines, or power cables for equipment
other than the programmable controller. Noise, surges, or induction may affect the system.
• Ground the shielded wires or shielded cables at one point on the programmable controller side. However,
depending on the external noise conditions, it may be better to ground them externally.
• For the voltage input, do not exceed a range of ±15V. Doing so can cause breakdown of the elements.
• For the current input, do not exceed a range of ±30mA. Doing so can cause breakdown of the elements.
(d) External wiring
The following figure shows the external wiring.
*1 For the cable, use the 2-core shielded twisted pair cable.
*2 This indicates the input resistance of the A/D converter module.
*3 For the current input, always connect the terminals (V+) and (I+).
*4 If noise or ripple is generated in the external wiring, connect a capacitor of approximately 0.1 to 0.47μF (product with a
voltage-resistance of 25V or higher) between the V+ and COM terminals.
*5 Ground the FG1 terminal without fail. If there is much noise, it may be better to ground the AG terminal as well.
If the grounding status of the AG terminal is changed after the offset/gain values are set, set the values again.
*3
*4
*
5
*
2
*
1
*
1
500k
500k
500k
250
250
500k
V+
I+
COM
SLD
V+
I+
COM
SLD
AG
FG1
For voltage input
Signal source: -10 to 10V
For current input
Signal source: 0 to 20mA
Shield
Shield
CH1
CH4
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