Model 3095FB Multivariable Transmitter with Modbus Protocol
Modbus Protocol Guide
Page 32 of 79
5.2 Process Variable Limit Checking
There are essentially four different limits for each process variable. These are the Upper
Range Limit(URL), Lower Range Limit(LRL), Upper Operating Limit(UOL), and the Lower
Operating Limit(LOL). The host can only change the Upper and Lower Operating Limits. The
Upper Range Limit and the Lower Range Limit are fixed and depend on the range of the sen-
sor module.
The UOL and LOL cannot cross each other. Here is the formula that the transmitter uses to
validate the operating limits sent by the host. The 3095FB will return the Modbus exception
Illegal Data Value(03) if invalid operating limits are sent.
Lower Operating Limit:
LRL <= LOL <= (UOL - min_span)
Upper Operating Limit:
(LOL + min_span) <= UOL <= URL
min_span = URL/100
0062
R/W, WP
Process
Tempera-
ture
20
21
Degrees Celsius
Degrees Fahrenheit
21
*Attributes: R/W = Read/Write, RO = Read Only, WP = Write Protected
**These registers are available at multiple Modbus addresses (see Section 2.3 located in the
Modbus Protocol Guide
)
Table 5-2 Unit Codes
Modbus Access
DESCRIPTION
Address
Attributes
Variable
Integer Codes
Default
