Control Techniques Epsilon EP-P, Reference Manual

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Epsilon EP-P Drive Reference Manual
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Figure 120: Modbus Master View - Slave Tab
Figure 121: Modbus RTU Timing Diagram
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a - Response Gap - Specifies the maximum timeout for the response packet. If a response packet is not detected within this
period then the slave device status is set to no_response.

b - Inter Character - Specifies the maximum period for receiving each character of the Modbus packet. If a character is not
received during this period, then the master considers the partial packet incomplete, and sets the slave device status to
no_response.

c - Inter Frame - Specifies the period of no data transmission indicating the end of the Modbus packet. Modbus specifications
generally specify this gap to be 3½ characters wide. If data is received during this period, then it is considered a part of the current
data packet.

d - Message Gap - Specifies idle period between the last packet received and the next packet transmitted. This gap allows for
extended quite time for multiple slaves on the same communications path; where slaves may be actively monitoring Modbus
packets and may miss the standard Inter Frame gap.
∆ a ∆ d ∆ c ∆ b
Slave
Master