Wire it right the first time
The weigh-bar, power, serial, and remote-display pin-outs we use across every brand — plus the full cable, pigtail, and connector catalog. When a stored number and the scale disagree, trust a known weight; when the colors and the pins disagree, trust this page and the diagram inside the J-box lid.
Weigh-bar / load-cell pin-out
The color code varies by brand — match the code to the exact bar you have. Avery Weigh-Tronix is the odd one: its excitation and signal colors differ from the Digi-Star family, so don’t assume red is always excitation.
Digi-Star (4-pin AMP)
| Wire | Function |
|---|
| Red | + Excitation |
| Black | − Excitation |
| White | + Signal |
| Green | − Signal |
| Bare / gray | Shield |
Dinamica Generale
| Wire | Function |
|---|
| Red | + Excitation |
| Black | − Excitation |
| Green | + Signal |
| White | − Signal |
| Bare / gray | Shield |
Avery Weigh-Tronix (5-pin)
| Wire | Function |
|---|
| Green | + Excitation |
| Black | − Excitation |
| White | + Signal |
| Red | − Signal |
| Orange / bare / gray | Shield |
Transcell / Tru-Test / Salter Brecknell
| Wire | Function |
|---|
| Red | + Excitation |
| Black | − Excitation |
| Green | + Signal |
| White | − Signal |
| Bare / gray | Shield |
Color codes differ by brand — don’t assume. Digi-Star (4-pin AMP): red = +Excitation, black = −Excitation, white = +Signal, green = −Signal. Dinamica Generale: red = +Excitation, black = −Excitation, green = +Signal, white = −Signal — mostly the same code as Transcell / Salter Brecknell (bare leads, ECP, or SPM plug). Avery Weigh-Tronix (5-pin): green = +Excitation, black = −Excitation, white = +Signal, red = −Signal. Transcell / Tru-Test / Salter Brecknell: red = +Excitation, black = −Excitation, green = +Signal, white = −Signal. If the weight counts backward, swap the signal pair.
Connector pins — Digi-Star M12 Ez-Mate
| Pin | Wire | Function |
|---|
| 1 | Red | + Excitation |
| 3 | White | + Signal |
| 4 | Green | − Signal |
| 5 | Black | − Excitation |
Connectors by brand: Avery Weigh-Tronix bars use a 5-pin end (mating plug MS3106A12-5P, size-12 shell, insert 12-5). Digi-Star bars use a 4-pin AMP or M12 Ez-Mate end; Dinamica Generale uses bare leads, an ECP connector, or a military-style (SPM) plug (switched at the connector vs. bare leads — most installs use bare leads into the J-box). Transcell / Tru-Test load bars use the C16 connector (female EKC00008P, male EKC21807).
Dinamica Generale connectors (M12)
From the DG factory pin-out (ticket #027771). M12 power and sensor cables:
Power cable
| Pin | Wire |
|---|
| 1 | Red |
| 2 | Green |
| 3 | Black |
| 4 | White |
Sensor / load-cell cable
| Pin | Wire |
|---|
| 1 | Red |
| 3 | White |
| 4 | Green |
| 5 | Black |
Source: Dinamica Generale ticket #027771; DG clone load-cell correspondence (969-0513 / 969-0583 / 969-0584).
Serial & remote-display pin-out (RS-232)
Indicator to scoreboard / LED remote, three wires — transmit, receive, ground:
| Signal | Indicator | Scoreboard |
|---|
| Transmit (TX) | 2 | 2 (or 3, crossed) |
| Receive (RX) | 3 | 3 (or 2, crossed) |
| Ground (GND) | 5 | 5 |
Settings: 9600 baud is typical. One scoreboard ran 1200 baud, 7 data bits, odd parity, 1 stop bit — if 9600 straight-through gives nothing, try the crossed pins (2↔3) and the 1200/7/odd/1 format. On Weigh-Tronix indicators the 9-pin round connector is the remote-display port; Digi-Star GT460/GT560 drive a remote through the J903/J904 port (8-pin TDM cable, opposite gender of the 8-pin serial).
Which pin transmits depends on the device. A PC or laptop is wired as DTE and transmits on pin 3; most indicators and scoreboards are wired as DCE and transmit on pin 2 — that is why an indicator-to-PC cable usually runs straight-through (2→2, 3→3), while two devices of the same type need a null-modem crossover (2↔3). If you get nothing on a fresh cable, the TX/RX pair is the first thing to swap. Always confirm the assignment against the specific indicator's manual before you crimp.
Serial (RS) & remote-display (RD) ports
Digi-Star labels the ports on the bottom of the head: J905 = Serial, J903 = Remote (J904 is the EZ-III serial-option port). All three are 8-pin AMP round connectors.
Digi-Star serial port — J905 (8-pin AMP)
| Pin | Signal |
|---|
| 1 | +5 VDC |
| 2 | Com 1 TX — out (computer) |
| 3 | Com 1 RX — in (DDL / computer) |
| 4 | Com 2 TX — out (printer) |
| 5 | +12 VDC |
| 6 | Ground |
| 7 | Com 2 RX — in |
| 8 | Ground |
Remote-display port (J903): same 8-pin AMP shell; carries the weight stream and power out to the RD-series remotes (RD440 / RD2400V) and the LED scoreboards. The Digi-Star RD Y-cable (1000-7550) and the 25' J903 extension (1000-8618-25) land here; the J904 (W/T & Digi) extension is 1000-8624-25.
Weigh-Tronix: the remote-display port is the 9-pin round (RD extension 1000-8621-25); the serial / print stream is standard 9600-baud RS-232 (TX 2, RX 3, GND 5). RS-232 port details are on manual pg 76.
Load-cell testing & wiring notes
Before chasing a bad reading through the indicator, ohm the cell out at the connector. These are the numbers and rules the bench uses.
4-wire vs. 6-wire cells
A 4-wire cell has one excitation pair (+Exc / −Exc) and one signal pair (+Sig / −Sig) — that covers almost every ag weigh-bar. A 6-wire cell adds a +Sense / −Sense pair that rides alongside excitation so the indicator can measure the voltage actually reaching the cell and compensate for voltage drop over a long cable run. If you land a 6-wire cell on a 4-wire indicator, jumper Sense to Excitation at the indicator (+Sense to +Exc, −Sense to −Exc) or the reading will drift with cable length and temperature.
Resistance / bridge check (cell unplugged)
| Measurement | Good reading |
|---|
| Across the excitation pair (input) | ~350–700 Ω (some cells 1 kΩ) |
| Across the signal pair (output) | ~350–700 Ω (some cells 1 kΩ) |
| Two bridge legs compared | within ~1 Ω of each other |
| Shield / bare to any wire | open (infinite) — continuity means a pinched or wet cable |
Digi-Star rule of thumb: if a bar reads more than about ±15% off its chart value, replace the bar rather than trying to trim it in. Ohm every cell in a multi-bar J-box — one shorted or open cell drags the whole scale.
Excitation voltage
Load-cell excitation is typically 5–15 V DC — 10 V is common on bench indicators and many field/ag indicators run around 5 V. It is model-specific; check the indicator's manual before assuming, and never drive a cell rated for 10 V from a higher-voltage supply.
ISO-BUS / CAN-BUS power connector
The tractor-side ISO-BUS implement connector is a 6-pin Deutsch. This is the standard power / CAN pin-out:
| Pin | Signal |
|---|
| 1 | CAN-L |
| 3 | Ground |
| 4 | +12 V (switched power) |
| 6 | CAN-H |
Heads-up: the ISO-BUS 6-pin above carries power and the CAN pair — it is not the load-cell signal. CAN-H / CAN-L is a twisted pair and wants a 120 Ω terminator at each end of the bus.
By-brand notes
The odds and ends worth keeping in one place.
- Avery Weigh-Tronix: 640 runs 9600-baud RS-232; RS-232 port details are on manual pg 76. Power is the W/T 2-pin (
14481-0025 digital power connector).
- Digi-Star / Topcon: GT400 / EZ-3 default print format
PRTAC1. J-box pigtail 12000-7372 (Digi-Star or Eaton). DIGI 4A fuse.
- Dinamica Generale: DG400 ECU pin-out is on manual pg 41. Load cells ship with a Digi-Star wiring diagram; M12 Ez-Mate.
- Salter-Brecknell / Tru-Test: C16 load-bar connectors; XRP–RS-232 serial cable; USB/RS-232 adapter for a PC.
- Transcell (Ti-500): 20'/35' J-box cables; +6V power cords; Ti-500-to-CP130 printer cord.
- Agrimatics / Libra: the Serial Link (M0080) streams the Libra’s weight to another display — e.g. a M12→DB9
P0080/P0081 to John Deere cable and monitor. UHarvest adapter via P0030, 12-pin Deutsch-to-4-pin AMP adapter. Serial Link cables: interface P0060, power P0070. P0050 is the moisture-sensor cable to an M0016.
- Scale-link / ISO-BUS: 6-pin Deutsch connector.
Junction-box rule of thumb
The diagram is on the inside of the lid. If a J-box scale won’t read right, first unhook the shield / ground wire; if that doesn’t do it, move the shield over to the black-wire terminal. Reseat every bar into the same excitation / signal positions before chasing anything deeper.
Cable & connector catalog
Everything on the shelf, by type — part number and description. (Pricing lives on the internal parts sheet.)
J-box cables
| Part # | Description |
|---|
| — | 25' 5-pin or AMP J-box cable |
| CCS527-1212 | 20' Ti-500 J-box cable |
| — | 35' Ti-500 J-box cable |
| — | 25' Ez-Mate to AMP J-box cable |
| 55932-0049 | 25' 5-pin M to Tru-Test load-cell end cable |
| 47100-0042 | 25' 5-pin M to 7-pin M cable |
| 28755-0024 | 25' 5-pin M to 5-pin M cable |
| — | 25' 5-pin M to AMP LC end cable |
| 17960-0010 | Additional cable (per foot) |
Junction boxes
| Part # | Description |
|---|
| — | 44 weigh-bar J-box w/ 25' cable |
| 19219-0014 / 19291-0015 | 3 or 4 weigh-bar J-box w/ 25' cable |
| 50040-0015 | 6 weigh-bar J-box w/ 25' cable |
| AWT15-500006701 | Spring J-box (no cable) |
| AWT15-4100672 | Spring J-box w/ 25' cable |
| 404721 | Ez-Mate J-block (no cable) |
Pigtails
| Part # | Description |
|---|
| 44258-1128 | W/T 4-pin weigh-bar end pigtail |
| 23581-0017 | 5-pin weigh-bar end pigtail |
| 33678-1919 | Tru-Test / Gallagher pigtail |
| 12000-7372 | Digi-Star or Eaton J-box pigtail |
| 19266-00327 | W/T digital power pigtail |
| 50474-0033 | AMP power pigtail |
| — | Ez-Mate pigtail |
Y-cables
| Part # | Description |
|---|
| 100-7755 | 640 remote-display Y cable |
| 100-7551 | 640 / Digi-Star J904 / RS Y cable |
| 1300-1515-11 | DB15 Y cable |
| 1000-7550 | Digi-Star remote-display Y cable |
Extensions
| Part # | Description |
|---|
| 15186-0103 | 15' 5-pin F to 5-pin M extension |
| 21575-0028 | 15' AMP LC F to AMP LC M extension |
| 1000-8618-25 | 25' 8-pin AMP J903 (Digi remote) extension |
| 1000-8624-25 | 25' 8-pin AMP J904/J904 (W/T, Digi) extension |
| 1000-8621-25 | 25' 9-pin AMP (W/T remote) extension |
Adapters
| Part # | Description |
|---|
| 101-5400 | 5-pin F to AMP LC M adapter |
| 101-0045 | AMP LC F to 5-pin M adapter |
| AWT77-0033 | 5-pin F to Ez-Mate end adapter |
Connectors
| Part # | Description |
|---|
| MS3106A12-5P | W/T & Avery weigh-bar 4-pin mating plug (size 12, insert 12-5) |
| 11891-0018 | W/T 4-pin male weigh-bar end |
| 11891-0019 | 5-pin male weigh-bar end |
| 14522-0059 | 5-pin weigh-bar base connector |
| 14452-0020 | 5-pin weigh-bar end connector |
| 206429-1 | AMP LC male J-box cable end w/ inserts |
| 17762-0222 | 5-pin female indicator base connector |
| 14481-0025 | W/T 2-pin digital power connector |
| 206060-1 | AMP power end connector w/ inserts |
Power cables
| Part # | Description |
|---|
| WT 19266-0041 / DS 50474-0036 | W/T – Digi-Star power cord, plain 10'–12' |
| WT 19266-0044 / DS 18355-0000 | W/T – Digi-Star battery power cord |
| WT 12342-0011 / DS 18355-0047 | W/T – Digi-Star tractor power cord |
| — | 25' W/T power cord |
| 706896 | Ti-500 +6V power cord |
| 706897 | Ti-500 +6V power cord w/ cig-lighter plug |
| 808111 | Salter +12V power cord |
| 808222 | Salter +12V power cord w/ cig-lighter plug |
| 1000-8275 | In-cab remote power cord |
Printer & computer cables
| Part # | Description |
|---|
| AWT77-504294 | RS-232 to DB9 computer cable |
| — | Printer cord, DB15 or 8-pin AMP to TMU295 |
| AWT25-501073 | Printer cord, 8-pin AMP (DS or W/T) to CP130 |
| AWT25-501075 | Printer cord, DB15 to CP130 |
| AWT25-501828 | Printer cord, 8-pin AMP W/T to CP103 |
| AWT25-501824 | Printer cord, 8–9N AMP Digi-Star to CP103 |
| AWT25-501826 | Printer cord, DB15 to CP103 |
| AWT25-501077 | Printer cord, 8-pin AMP Digi-Star to CP130 AC |
| — | Printer cord, Ti-500 or Salter 200 to CP130 |
Remote-display cables & harnesses
| Part # | Description |
|---|
| 55101-0093 | 30' cable assembly (RD40XL / RD64XL / RD64M) |
| 55101-0093 | 50' cable assembly (RD64XL) |
| 54847-6060 | Remote-display harness w/ Molex connector |
| 1000-6756 | Magnets for 4″ remote display (ea) |
| — | Wireless hub (for wireless remote) |
Internal harnesses
| Part # | Description |
|---|
| 27639-0051 | DB15 cable assembly |
| 54948-7171 | RS-232 harness w/ Molex connector |
| 51837-1313 / 21429-0090 | (51) harness w/ Molex connector |
| 54948-1212 / 21429-0124 | (54) harness w/ Molex connector |
| 50044-0037 | AMP LC harness |
| 57737-0018 | Digi power harness |
| 57737-0026 | AMP power harness |
Tru-Test / Salter-Brecknell
| Part # | Description |
|---|
| 808368 | Cable assembly, 800 / 1010 load bar |
| 812545 | Cable assembly, 600 load bar |
| 816773 | XRP–RS-232 DBP serial cable |
| 824429P | USB / RS-232 adapter cable |
| EKC00008P | C16 female cable connector |
| EKC21807 | C16 male cable connector |
| EKZ31070P | Load-bar connector dust cap (all models) |
| 805741 | SKU XHD10000 J-box (includes cable) |
| 826910 | Spare J-box kit XHD2 (J-box & cable) |
Agrimatics / Libra
| Part # | Description |
|---|
| P0030 | UHarvest adapter — 12-pin Deutsch to 4-pin AMP |
| P0050 | Moisture Sensor to Digi — sensor cable to Libra M0016 |
| P0060 | Serial Link interface cable (M0080) |
| P0070 | Serial Link power cable (M0080) |
| P0080 / P0081 | Serial Link (M0080) M12→DB9 cable — John Deere weigh-share |