5.1.3 FF Segment Checklist
There can be several reasons for a FOUNDATION fieldbus™ installation to be in a faulty condition. In order to assure that communication can be established, the following requirements must be met.
•Device supply voltage must be higher than 9 VDC with a maximum of 32 VDC.
•Total current draw of a given segment cannot exceed the rating shown on the power conditioner and/or barrier.
•Two 100 Ω, 1 µF terminators must be connected to the
•Cable length plus spur length must not exceed the following values:
Number of Spurs | 1 Device | 2 Devices | 3 Devices | 4 Devices |
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100 ft. (30 m) | — | — | — | |
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200 ft. (60 m) | 100 ft. (30 m) | — | — | |
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300 ft. (90 m) | 200 ft. (60 m) | 100 ft. (30 m) | — | |
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400 ft. (120 m) | 300 ft. (90 m) | 200 ft. (60 m) | 100 ft. (30 m) | |
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Pair | Shield | Twisted | Size | Length | Type | |
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Single | Yes | Yes | AWG 18 | (0.8 mm2) | 6,200 ft. (1,900 m) | A |
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Multi | Yes | Yes | AWG 22 | (0.32 mm2) | 3,900 ft. (1,200 m) | B |
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Multi | No | Yes | AWG 26 | (0.13 mm2) | 1,300 ft. (400 m) | C |
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Multi | Yes | No | AWG 16 | (1.25 mm2) | 650 ft. (200 m) | D |
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•The cable shield is to be hard grounded only at one point close to the DCS. In addition, the cable shield can be capacitively grounded in multiple places to improve EMC protection.
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