Comms cable selector
Pumili ng comms cable at tingnan ang haba ng run.
Reads AS/NZS 3000:2018 and Industrial communications sources 2019-2024. Tables checked 26 Sept 2026.
Subukan ang isang job 8
Nilalagyan ng halimbawang value ang bawat job. Palitan ang mga ito ng sarili mong value.
- Add an instrument loopA cable for the signal over a 150 m route.
- Select a comms cableA PROFINET cable for a 60 m run through a drag chain.
- Check an RS-485 runWhether 400 m at 115.2 kbps is in the limit.
- Check a long Modbus trunkWhether 1200 m at 9.6 kbps is in the limit.
- Check an Ethernet run past 90 mWhether a 110 m Ethernet run is in the limit.
- Pick a 24 V field supply cableA cable for a 24 V d.c. supply over 80 m.
- Pick a screened cable beside a driveA screened signal cable for a noisy area.
- Pick an outdoor Ethernet cableAn Ethernet cable for an outdoor run.
Mga input
Worked example gamit ang mga default na input.
- Interface
- RS-485
- Environment
- Fixed na installation
- Haba ng run
- 100 m
- Materyal ng sheath
- PVC
- Naka-screen ang cable
- Oo
- Bilis ng transmission
- 187.5 kbps
- Pamilya ng bus cable
- Standard, robust, FRNC, food, underground o marine
Haba ng run
Nasa loob ng limit
- Limit ng haba
- 1,000m
- Konstruksyon ng cable
- 1 pair or more, 2 cores, larger than 0.34 mm2, required screen
- Screen
- Kinakailangan
- Screen check
- Pasa
- Termination sa bawat dulo
- 120Ω
- Unit loads bawat linya
- 32
- Pagsusuri ng kapaligiran
- Pasa
- Check ng kategorya
- Hindi naaangkop
- Tala
- A PROFIBUS DP segment at 187.5 kbps on standard bus cable may run 1000 m, from a cable maker network manual. The held table falls from 1000 m at 9.6 kbps to 100 m from 3 Mbps up. TIA-485 itself sets no maximum line length, and a separate report gives a nominal 1.2 km on 24 AWG cable.
Design aid lang ang resultang ito. I-verify ito laban sa kasalukuyang standard.
Mga hakbang ng kalkulasyon
- InterfaceRS-485
Industrial communications sources 2019-2024
- Haba ng run100m
- Limit ng haba1,000m
Industrial communications sources 2019-2024
- Pagsusuri ng habaPasado
- Konstruksiyon1 pair or more, 2 cores, larger than 0.34 mm2, required screen
Industrial communications sources 2019-2024
- Kailangan ng screenrequired
Industrial communications sources 2019-2024
- Pagsusuri ng screenPasado
- KapaligiranFixed installation
Industrial communications sources 2019-2024
- Environment checkPasado
- Check ng kategoryaHindi naaangkop
- Bilis ng transmission187.5 kbps
- Printed speed row187.5 kbps
Industrial communications sources 2019-2024
- Pamilya ng bus cablestandard bus cable
Industrial communications sources 2019-2024
- Termination sa bawat dulo120Ω
Industrial communications sources 2019-2024
- Unit load kada linya32
Industrial communications sources 2019-2024
- Mga attachment ng bus bawat segment32
Industrial communications sources 2019-2024
Tungkol sa calculator na ito
How this is calculated
The tool picks the cable construction for a control or data link. It checks your run length against the limit for the interface. No AmpSize figure here comes from a printed Standard. The figures come from maker data and course notes, which the tool labels as secondary sources.
- Interface. You pick 24 V d.c., 4–20 mA, RS-485, Ethernet or PROFINET. For RS-485 you also pick the data rate and the bus cable family.
- Length limit. The tool reads the longest run for that interface. For RS-485 the limit falls as the data rate rises.
- Length check. It compares your run with the limit. It reports the run as inside or over the limit.
- Construction. It gives the pairs, the cores and the smallest core size. It says whether a screen is required, and checks the screen you enter.
- Environment. It checks the sheath and the bend radius for a fixed or a flexing installation. For Ethernet it checks the category.
- Termination. For RS-485 it gives the termination at each end and the unit loads per line.
| Step | Source | What it decides |
|---|---|---|
| Length limit | Industrial communications sources 2019 to 2024 | The longest run for the interface |
| Construction and screen | Industrial communications sources 2019 to 2024 | The cable build |
| Termination | Industrial communications sources 2019 to 2024 | The resistor at each end |
Worked example
- RS-485 at 187.5 kbps over 1200 m. The limit is 1,000 m, so the run is over the limit. The screen and environment checks pass. Add a repeater or shorten the run.
Limits
- The figures are secondary source and maker data. They are not a Standard. Confirm each one with the device maker.
- The tool does not size power conductors. Use the DC cable size calculator for a 24 V supply.
- The tool does not check segregation from power cables. Use the segregation checker.
- The termination value suits typical cable. Match it to the cable you use.
- The 32 unit loads on an RS-485 line are not a device count.
See also: Control panels and PLC wiring, 24 V DC instrument loop voltage drop and Loop power.
Mga tanong
Design aid ang resulta. I-verify ito laban sa kasalukuyang standard.
Ano ang ginagawa ng comms cable selector?
Binabanggit nito ang konstruksyon ng cable para sa 24 V DC, 4–20 mA, RS-485, Ethernet o PROFINET link, at sinasabi kung nasa loob ng limit ng interface na iyon ang haba ng run. Tinitingnan din nito ang sheath, screen at bending radius laban sa environment.
Gaano kahaba ang maaaring RS-485 segment?
Iniuulat ng tool ang PROFIBUS DP segment length mula sa manual ng cable maker: 1000 m hanggang 187.5 kbps sa standard bus cable, 400 m sa 500 kbps, 200 m sa 1.5 Mbps, at 100 m mula 3 Mbps pataas. Mas maikli ang run ng flexible at torsion cable.
Ano ang binibilang ng RS-485 limit na 32?
Unit load, hindi device. Ang isang unit load ay kumukuha ng 1 mA sa ilalim ng common-mode stress na 12 V. Ang receiver na may input resistance na higit sa 12 kilohm ay nagpapakita lamang ng bahagi ng isa, kaya puwedeng magdala ang isang line ng higit sa 32 receiver.
Anong termination ang kailangan ng RS-485?
Katumbas ng characteristic impedance ng line ang termination resistance. Ang held source ay gumagana sa 120 ohm sa bawat dulo, kaya itugma ito sa cable na ginagamit mo. Ang line na sapat ang ikli para ituring na lumped-parameter ay hindi nangangailangan ng termination.
Anong length limit ang nalalapat sa 24 V DC at 4–20 mA?
Walang inilathalang haba ang alinman sa dalawa. Ang 24 V DC run ay nililimitahan ng voltage drop, kaya gamitin ang voltage drop tool ng AmpSize sa 24 V. Ang 4–20 mA loop ay nililimitahan ng loop burden at ng transmitter supply voltage.
Background
Mga clause at table na binabasa ng tool na ito
- AS/NZS 3000:2018 Table 3.3Nominal minimum cross-sectional area of conductors
- Industrial communications sources, interface limitsLength, screen and construction limits for five industrial interfaces
Bawat clause at table, kasama kung paano ito na-verify
Huling na-check ang mga table noong 26 Sept 2026.
Mga kaugnay na tool
- Loop power budget para sa 4-20 mA loopsCheck the voltage a 4–20 mA loop leaves the transmitter.AS/NZS 3008.1.2AS/NZS 3008.1.1
- Voltage drop calculatorCalculate voltage drop on a cable run and check the limit.AS/NZS 3008.1.2AS/NZS 3008.1.1AS/NZS 3000
- Cable screen earthing selectorFind where to earth a screen, drain wire or armour.AS/NZS 3000
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