6 20ma current loop, 4 fiber optics assembly, 20ma current loop – Rice Lake 320IS Plus Intrinsically Safe Digital Weight Indicator - Installation Manual User Manual

Page 81

320IS Plus Installation Manual - Appendix B

Figure 9-3. Typical RS-422 Wiring Paths

9.3.6

20mA Current Loop

To attach a PC or other device to the

I/O Module

’s 20mA ports, select current loop (CRLOOP) standard in the

indicator SERIAL menu for the desired port (EDP and/or printer). EDP and printer ports should be configured

separately. See Table 9-6 below for information on connecting 20mA current loop.

9.4

Fiber Optics Assembly

The

I/O Module

is equipped with duplex fiber optic ports for communicating with other devices located in the

safe or hazardous area. It provides electrical isolation and eliminates the use of I/O barriers commonly used in

intrinsically safe systems. The fiber optic wires are plastic; no polishing or further preparation is required. See

Figure 9-1 on page 73 for the location of the fiber optic ports on the

I/O Module

main board.

The fiber optic connections between the indicator and the

I/O Module

need to be cross-linked.

The optical output of the indicator should be attached to the input of the

I/O Module

, and the indicator’s

input to the module’s output.

Use the following steps for assembling the fiber optics connectors of the

I/O Module

1. Cut off the ends of the fiber optic cable with a single-edge razor blade or sharp knife. Try to obtain a

precise 90º angle.

Description (Sign)

Signal Ground (GND)

—

RS-422 input (R+)

RS-422 input (R-)

RS-422 output (T+)

RS-422 output (T-)

Table 9-5. RS-422 Connections (CN2 and CN3)

Description (Sign)

Signal Ground (GND)

Isolated Ground (GNDx)

Receive Data (RCL) Passive

Transmit Data (TCL) Active

—

Table 9-6. 20mA Current Loop Connections (CN2 and CN3)

I/O Modul e

Note