Bently Nevada 3300/01 Series, Operation Manual

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System Monitor
80175-01
16 PROTOCOL SPECIFICATIONS
MODBUS PROTOCOL DATA FORMAT
Internally the Serial Interface converts the backplane multiplexed static data signal into a digital
value using an 8-bit analog-to-digital convertor. When an analog data request message is received
on Modbus protocol, this 8-bit value is shifted left 4 bits to represent a 12-bit value.
Since the maximum value the 8-bit convertor can have is 255, then the maximum 12-bit value is
255(16) = 4080. The least significant four bits of the 12-bit binary word are always zero.
MODBUS PROTOCOL MESSAGE RESPONSE TIMES
The following specifications define t h e typical measured response times f o r messages. T h e
response time is the time from the end o f the last received message t o the beginning o f the
subsequent response message. It does not include message transmission times.
Type of Read
Response Time (msec)
36 Registers
36 Points 14
8
44