42
SUPERtrol-I LE Flow Computer
10. RS-485 Serial Port (optional)
10.1 RS-485 Port Description:
The ST1LE has a an optional general purpose RS-485 Port which may be used for any one of the
following purposes:
Accessing Process Parameters
Rate, Temperatures, Density, Setpoints, Month, Day, Year, Hour, Minutes, Seconds, etc.
Accessing System Alarms
System, Process, Self Test, Service Test Errors
Accessing Totalizers
Totalizer and Grand Totalizer
Executing Various Action Routines
Reset Alarms, Reset Totalizers, Print Transaction, Reset Error History, Start, Stop, Clear
10.2 General
The optional RS-485 card utilizes Modbus RTU protocol to access a variety of process parameters
and totalizers. In addition, action routines can be executed. For further information, contact facto-
ry and request RS-485 Protocol manual for ST1LE.
10.3 Operation of Serial Communication Port with PC
The flow computer's RS-485 channel supports a number of Modbus RTU commands. Refer to
port pinout (below) for wiring details. Modbus RTU drivers are available from third party sources
for a variety of Man Machine Interface software for IBM compatible PC's.
The user reads and writes information from/to the RS-485 using the Modbus RTU commands.
The ST1LE then responds to these information and command requests.
Process variables and totalizers are read in register pairs in floating point format. Time and date
are read as a series of integer register values. Alarms are individually read as coils. Action rou-
tines are initiated by writing to coils.
10.4 ST1LE RS-485 Port Pinout
1
2
3
4
5
6
7
8
9
1 Ground
2 Ground
3 Ground
4 TX/RX (+)
5 TX/RX (-)
6 Do Not Use
7 Terminating Resistor (180 Ω)
8 TX/RX (+)
9 TX/RX (-)
Connect terminal 7 to either
terminal 4 or 8 to provide
required cable termination
Mounting Style "W"
Wall Mount Terminal
Block Connector
Mounting Style "P" (Standard)
Panel Mount DB9 Connector (female)
Mounting Style "P" (TB Option)
Panel Mount Terminal
Block Connector
