Communication Method - 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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Document revision
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The master sends a query message (question), and the subordinate returns a response message (response). When communication is normal, Device Address and Function Code are copied. When communication is abnormal (function code or data code is illegal), bit 7 (=80H) of Function Code is turned on, and the error code is set to Data Bytes.
Figure 1. Communication Message Structure

The message frame consists of the four message fields as shown in Figure 1. By adding the no-data time (T1: Start, End) of 3.5 characters to the beginning and end of the message data, the subordinate recognizes it as one message.