6. Appendix
The following table indicates the communications setting used by Astat Plus to perform data communication via its serial port
Name Setting Description
Baud Rate 9600 bps Bits per second transmission rate
Parity None Data error checking method
Data Bits 8 Number of data bits in each transmission
Start Bits 1 Number of bits to indicate beginning of transmission
Stop Bits 2 Number of bits to indicate ending of transmission
Data ASCII / RTU Communications protocol used
Handshaking None No need to request to send or clear to send
Computer 2 TD ASTAT Plus
Pin
RS232 cable
6-4
6-2. Serial Communication
Astat Plus is able to send and receive data through a serial RS232 port. Within this port Astat Plus communicates with a host (which can be
either with a PC / PLC or an industrial fieldbus system) to be started, stopped, programmed or checked.
3 different communication possibilities are available:
- Connection to a PC / PLC using ASCII protocol. (PC Windows communication software tool available)
- Connection to a PC / PLC using Modbus RTU protocol.
- Connection to industrial fieldbus systems (Profibus DP / DeviceNet). In this case it is necessary to use an external communications
module. Astat Plus communicates with this module using Modbus RTU protocol, and the module acts as a gateway to the fieldbus system.
In order to select the desired procedure the user must change the value of the parameter XP.
Protocol XP setting
ASCII 0
Modbus RTU 1
Profibus/DeviceNet 2
6-2-1. RS232 port, wiring and communications settings
RS232 is an operating standard of communication only in terms of electrical characteristics (voltage, timing, etc.) while the communication
procedures are defined by different protocols (Modbus, ASCII, Profibus, DeviceNet, etc.).
The maximum allowed RS232 cable length is 3 meters. Astat Plus uses a connector with only 3 pins: TD, RD, SG.
Astat Terminal Name
TD Transmit Data
RD Receive Data
SG Signal Common
RS232 connector 3 RD
D-SUB9 5 SG
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