Models FL3100/3101
31
In order to prevent this condition from occurring the typical response times for the
FL3100, FL3101 are listed below:
Baud
Rate
(bps)
Query From
Master
(msec)
Unit
Response
Delay Time to
Query (msec)
Response
From Unit
(msec)
Master Response
Delay Time Between
End of Unit
Response and Next
Master
Query (msec)
Total
Response
Time
(msec)
19.2K
4
4
4
100 - 120*
112 – 132
9600
8
5
8
100 - 120*
121 – 141
4800
16
6
16
100 - 120*
138 – 158
2400
32
8
32
100 - 120*
172 – 192
NOTE* - Master Response Delay Time is dependent on the speed of response
for the Master (DCS, PLC, etc.) Cycle Time can be significantly reduced with a
faster Master. The 100ms Delay Time was taken from a typical Master, using a
PC with Intellution Industrial Control Software, which was set at the minimum poll
time.
4.
If the FL3100, FL3101 receives the query without a communications error,
but cannot process it due to reading or writing to a non-existent or illegal
FL3100, FL3101 Function Code, Illegal Command Starting Address or
Register Address, or Illegal Data Value, then the FL3100, FL3101 will return
an exception response message informing the master of the error.
The exception response message has two fields that differentiate it from a
normal response, which is explained in Section 8.5.1.
8.5.1 Exception Responses
Byte
MODBUS
Range
Referenced to FL3100, FL3101
1
st
Slave Address
1-247* (Decimal)
FL3100, FL3101 ID (Address)
2
nd
Function Code
83 or 86 (Hex)
MSB is set with Function Code
3
rd
Exception Code
01 - 06 (Hex)
Appropriate Exception Code (See
below)
4
th
CRC Lo
00-FF (Hex)
CRC Lo Byte
5
th
CRC Hi
00-FF (Hex)
CRC Hi Byte
Function Code Field: In a normal response, the FL3100, FL3101 echoes the
function code of the original query in the function code field of the response. All
the Function Codes have a most-significant bit (MSB). In an exception response,
the FL3100, FL3101 sets the MSB of the function code to a one (1). With the
function code’s MSB set, the master can recognize the exception response and
can process the data field for the exception code from the FL3100, FL3101
response message.