User`s manual

RS-422/485 Communications Unit Chapter 7-1

Using a SI-485/J7 (3G3JV-PSI485J) RS-422/485 Communications Unit allows

J7AZ Inverters to participate in RS-422/485 serial communications. This

makes Inverter control input, frequency reference input, monitoring of the

Inverter’s operating status, and reading and writing of parameter settings all

possible via communications. Up to 32 Inverters can be connected to the Unit

to enable easy creation of networks.

Note 1. The RS-422/485 communications used by J7AZ Inverters conforms to the

MODBUS (a trademark of AEG Schneider Automation) communica-tions

protocol. No other communications protocol can be used in the same

network and only Inverters and related products can be used as Slaves.

2. The communications processing time with RS-422/485 communications

for J7AZ Inverters is proportional to the number of Slaves. When

performing Inverter control, consider the communications processing time,

and restrict the number of Inverters connected according to the response

times required.

3. The communications timeout time with RS-422/485 communications is

fixed at 2 s (when communications timeouts are enabled). In the worst

case, problems with the communications line may not be detected for up

to 2 s. Design the application and overall system to ensure safety allowing

for this.

7-1 RS-422/485 Communications Unit

7-1-1 Overview

• The SI-485/J7 (3G3JV-PSI485J) RS-422/485 Communications Unit is an

Optional Unit for J7AZ Inverters.

• Mounting an RS-422/485 Communications Unit to a 3G3JV Inverter

provides the Inverter with an RS-422/485 interface.

7-1-2 External Dimensions

21.5

4 x 3.8 = 15.2

819 8