Appendix 4: VFD68Bxx and VFD68Cxx ModBus RTU RS485 Communications Bus Specifications - PENN Controls - VFD68Bxx - VFD68Cxx - VFD68Dxx - Three‐Phase Motor Speed Controller - VFD68 Three‐Phase Variable Frequency Drive

VFD68 Variable Frequency Drives Technical Bulletin

PENN Controls
Product name
VFD68 Three‐Phase Variable Frequency Drive
Document type
Technical Bulletin
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Revision date
You must create a custom RS485 communication cable to connect the VFD68Bxx or VFD68Cxx to the head end of a ModBus RTU network.
Figure 1. VFD68Bxx and VFD68Cxx Identification of RJ45 Receptacle

Important: Do not connect pin 2 or pin 8 to a communication cable. Pin 2 and pin 8 of the RJ45 receptacle are connected to a power supply in the VFD68 drive. Connecting one or both of these pins to a communication cable may damage the VFD68 drive.
Table 1. VFD68Bxx and VFD68Cxx RJ45 Pin Identifications for Communications Bus
Pin Number Name Description
1 SG Earth (ground)

(connected to terminal 5)

2 Power supply
3 RDA VFD receive (+)
4 SDB VFD send (-)
5 SDA VFD receive (+)
6 RDB VFD send (-)
7 SG Earth (ground) (connected to terminal 5)
8 Power supply

Using the Modbus RTU communication protocol, you can set the communication operation or parameter using the operation panel on the VFD68 drive. These parameters can be set when P.160 = 0.

Table 2. Parameters for ModBus RTU RS485 Communications
Parameter Number Name Default Range  
P.117 PU communication station number 0 0 No reply to the master1
1 to 247 VFD station number specification

Set the VFD station numbers when two or more VFDs are connected to one computer.

P.118 PU communication speed 96 48, 96, 192, 384 Communication speed

The setting value x 100 equals the communication speed. For example, if the communication setting is 96, the communication speed is 9600 bps.

P.120 PU communication parity check 2 0 Without parity check; Stop bit length: 2 bits
1 With odd parity check; Stop bit length: 1 bit
2 With even parity check; Stop bit length: 1 bit
P.1222 PU communication check time interval 9999 0  
0.1 to 999.8  
P.343 Communication error count 0 ___ Displays the number of communication errors during Modbus RTU communication (reading only)
P.502 Stop mode selection at communication error 0   At Fault Occurrence Indication Fault Output At Fault Removal
0 Coasts to stop E.PUE Output Stop (E.PUE)
1 Decelerates to stop After stop, E.PUE Output after stop Stop (E.PUE)
2 Decelerates to stop After stop, E.PUE Without output Automatic restart functions
P.549 Protocol selection 0 0 VFD (computer link operation) protocol
1 Modbus RTU protocol
1 When Modbus RTU communication is performed from the master with address 0 (station number 0) set, broadcast communication is selected and the VFD does not send a response message. When a response from the VFD is necessary, set a value other than 0 in P.117. Some functions are invalid for broadcast communication.
2 Specifications differ according to the date assembled.