BRONKHORST®
9.17.061
EL-FLOW
Base
Series Mass Flow Controllers
Page 23
3.5.3 Implementation class
The physical and data link layer are implemented conforming to the "basic slave" implementation class
as described in document [2], “MODBUS over Serial Line specification and implementation guide V1.02”.
The following options have been implemented:
More detailed information about Modbus can be found at
http://www.modbus.org
or any website of
the (local) Modbus organisation of your country (when available).
3.5.4 Response time
This slave device will respond on each valid request from the master within 100 msec. This means that
the response timeout setting of the master should be set to a value larger than or equal to 100 ms.
3.5.5 Supported Modbus functions
This section describes the supported Modbus function codes. Refer to document [1] “MODBUS
Application Protocol Specification V1.1b, December 28, 2006” for more details.
More detailed information about Modbus can be found at
http://www.modbus.org
or any website of
the (local) Modbus organisation of your country (when available).
Read Holding Registers (03)
Possible exception responses:
02, ILLEGAL DATA ADDRESS, in case of reading of non-existing address, or reading a part of a
multiregister parameter (float, long, etc)
03, ILLEGAL DATA VALUE, in case of reading less than 1 or more than 125 registers
04, SLAVE DEVICE FAILURE, in case of reading a write-only register
!
The maximum message size for the Read Holding Registers function is 100 bytes at 9600 baud (200
bytes at 19200 baud and 400 bytes at 38400 baud). When this size is exceeded, corrupted responses
may be received.
Write Single Register (06)
Possible exception responses:
02, ILLEGAL DATA ADDRESS, in case of writing to non-existing address, or writing to a part of a
multiregister parameter (float, long, etc)
04, SLAVE DEVICE FAILURE, in case of writing to read-only register
04, SLAVE DEVICE FAILURE, in case of writing illegal value to register
Write Multiple Registers (16)
Possible exception responses:
02, ILLEGAL DATA ADDRESS, in case of writing to non-existing address, or writing to a part of a
multiregister parameter (float, long, etc)
03, ILLEGAL DATA VALUE, in case of reading less than 1 or more than 123 registers
Parameter
Options
Remarks
Addressing
address configurable from 1 to 247
(default 1)
see section 3.5.1
broadcast support
Yes
baud rate
9600, 19200 (default), 38400
see section 3.5.1
parity
None, Odd, Even (default)
see section 3.5.1
transmission mode
RTU/ASCII
Auto detection
data bits
RTU=8, ASCII=7
not configurable
electrical interface
RS485 2W-cabling
See document:
9.16.091 - Hook-up diagram EL-FLOW
Base
connector type
DB9 Male
See document:
9.16.091 - Hook-up diagram EL-FLOW
Base
