Catalog No. 29290
17
Rev 3 06/2020
b. RS-485/Modbus Connection
•
The RS-485 half-duplex (2-wire) digital interface operates with differential
levels that are not susceptible to electrical interferences. Cable lengths up
to 900 meters (3000 ft.) can be implemented.
•
The last device on each bus may require terminating with a 120-ohm
resistor to eliminate signal reflection on the line.
•
Do not run RS-485 cables in the same conduit as power.
•
Ensure that power is disconnected prior to making connections to present
damage to the instrument.
•
Connections are labeled beneath the large terminal block. These
connections are on the left side on the lower row.
c. 4-20 mA Connection:
Make sure the MTOL+ is disconnected and not powered BEFORE
connecting the 4-20 mA.
•
The 4-20 mA output is driven by a 24 VDC power source and can drive
recorder loads up to 1000 ohms.
•
This 4-20 mA output is isolated from line power and earth ground.
•
Do not run 4-20 mA cables in the same conduit as power.
•
Connections are labeled beneath the large terminal block. These
connections are on the right side on the lower row.
•
Operation of this output is covered in section 4.2.1
Setting the 4-20 mA
.
Summary of Contents for HF scientific 28052
Page 2: ...Catalog No 29290 Rev 3 06 2020 ...
Page 5: ...Catalog No 29290 Rev 3 06 2020 ...
Page 66: ...Catalog No 29290 59 Rev 3 06 2020 ...
Page 67: ......