RS-422/485 Communications Unit
Chapter 7-1
Note
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.
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
12 4 x 3.8 = 15.2
63 8 19 8
90
RS-422/485 Communications Unit
7-1-3 Names of Parts
Terminal block
Chapter 7-1
Terminating resistance switch
Terminal Block
1
S– S+
2
Terminating Resistance Switch
SW
OFF ON
Shield
3
R–
4
R+
5
Note Set the terminating resistance switch to ON to connect the terminating resistance.
7-1-4 Mouting Procedure
Use the following procedure to mount an RS-422/485 Communications Unit
SI-485/J7 (3G3JV-PSI485J) to a J7AZ Inverter.
1.
Turn OFF the Inverter’s power supply. Mounting the RS-422/485
Communications Unit without turning OFF the Inverter’s power supply may result in electric shock or damage to equipment.
2.
Loosen the Inverter’s front cover mounting screws and remove the front cover as shown on the left below.
3.
Remove the optional cover as shown on the right below.
A
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RS-422/485 Communications Unit
Chapter 7-1
4.
Align the Unit with the Inverter’s connector, and push the Unit onto the
Inverter (so that the 3 catches enter the corresponding holes) until it is securely mounted.
Note
Connector
5.
Mount the front cover (removed previously) on top of the RS-422/485
Communications Unit, and secure it using the front cover mounting screws.
(Do not mount the optional cover.)
When not using the RS-422/485 Communications Unit, be sure to mount the optional cover. Not mounting the optional cover will leave charged parts exposed and may result in electric shock or damage to equipment.
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