Mettler Toledo IND570 Manual Del Usuario página 48

2.4.5.1.2. DC Powered Models
24 VDC power is only available on panel mount models. The DC terminal requires 24 VDC, -15%,
+20% (at 1.25A maximum).
No power cables are included with the 24 VDC powered IND570 terminals. The 24 VDC power and
ground must be brought directly to the power connection of the main board and terminated there.
Figure 2-24 and show the three position terminal block provided for the DC power connection. A
wire is not terminated to the center position.
2.4.5.2. Analog Load Cell Connections
TO AVOID DAMAGE TO THE PCB OR LOAD CELL, REMOVE POWER FROM THE IND570 TERMINAL AND WAIT AT
LEAST 30 SECONDS BEFORE CONNECTING OR DISCONNECTING ANY HARNESS.
When using an analog load cell version of the IND570, load cell connections are made to the
connector located on the main board as shown in Figure 2-23.
The IND570 terminal is designed to power up to twelve 350-ohm load cells (or a minimum
resistance of approximately 29 ohms). To confirm that the load cell load for this installation is
within limits, the total scale resistance (TSR) must be calculated. To calculate TSR:
Ensure that the TSR of the load cell network to be connected to the IND570 has a resistance greater
than 29 ohms before connecting the load cells. If the resistance is less than 29 ohms, the IND570
will not operate properly.
In addition, the maximum cable distance must be reviewed. Table 2-3 provides recommended
maximum cable lengths based on TSR and cable gauge.
A jumper is provided that adjusts the gain of the analog section for 2 mV/V or 3 mV/V load cells.
The factory default position of this jumper is 3 mV/V. Normally this position will work well for both 2
mV/V and 3 mV/V load cells. If 2 mV/V load cells are used, the jumper can be changed to the 2
mV/V position. Refer to Figure 2-61 for the jumper position.
Figure 2-28 shows the terminal definitions on the analog load cell terminal strip. Note that when
using four-wire load cells, jumpers must be placed between the +Excitation and +Sense terminals
and between the −Excitation and −Sense terminals.
2-18 METTLER TOLEDO IND570 Weighing Terminal Installation Manual
TSR =
Table 2-3: Recommended Maximum Cable Lengths
TSR (Ohms) 24 Gauge (meters/feet)
350
87 (4-350 Ω cells)
43 (8-350 Ω cells)
29 (12-350 Ω cells)
NOTICE
Load Cell Input Resistance (Ohms)
Number of Load Cells
20 Gauge (meters/feet)
243/800 610/2000
60/200 182/600
30/100 91/300
20/67 50/167
16 Gauge (meters/feet)
1219/4000
304/1000
152/500
102/333
30205319 | 04 | 08/2016