Rice Lake SCT-10 - Manual (Page 38)

34 SCT Weight Transmitter Operator’s Manual
* For RIP remote displays, if the message exceeds 5 digits the display
reads
------
.
If an alarm becomes active the relays open and the analog outputs
go to the lowest possible value according to the following table:
3.6 Modbus-RTU Protocol
The MODBUS-RTU protocol enables to manage the reading and writing of the
registers listed here below according to the specifications contained in the
reference document for this standard Modicon PI-MBUS-300.
To select the communication with MODBUS-RTU, refer to Section 2.4 “Analog
Output” on page 21.
When specifically indicated certain data will be written directly to EEPROM
type memories. This memory has a limited number of writing operations
(100.000), therefore unnecessary operations at said locations must be avoided.
The instrument, in any case, ensures that no writing occurs if the value to be
stored is equal to the stored value.
The numerical data listed below are expressed in decimal notation, or
hexadecimal notation if preceded by 0x.
Modbus-RTU Data Format
The data received and transmitted via MODBUS-RTU protocol have the
following characteristics:
- 1 start bit
- 8 data bits, least significant bit sent first
- Instrument settable parity bit
- Instrument settable stop bit
ErCEL Er OL Er Ad
---------
Er OF t -----
MODE
Bit LSB 76543210
xxxxxxx1
76543210
xxxx1xxx 76543210
xxxxxx1x 76543210
xxxxx1xx 76543210
On gross:
xxx1xxxx
On net:
xx1xxxxx
The response
to the zero
command is a
'value not
valid' error
(error code 3)
Status
Register
MODBU
S RTU
ASCII
__O-F_ __O-L_ __O-F_ __O-L_ __O-F_ &aa#CR
RIP *
__O-F_ __O-L_ __O-F_ __O-L_ __O-F_ __O-F_
HDRIP-N _ERCEL _ER_OL _ER_AD ###### _ER_OF O__SET
CONTIN _ERCEL _ER_OL _ER_AD ^^^^^^ _ER_OF O__SET
Table 3-2. Serial Protocols Alarms
Range 0/20mA 4/20 mA 0/5 V 0/10 V -10/10 V -5/5 V
Output
Value
-0.2 mA 3.5 mA -0.5 V -0.5 V 0 V 0 V
Note