SATEC SLC500 - Manual (Page 6)

6
2.4 Powermeters Communications Settings
The Powermeters should be configured properly to operate with the BASIC module. The
Powermeters communications settings must be compatible with the BASIC module port PRT2
interface settings (RS-422/485/232) and the driver EPROM version used.
The Powermeter communications settings are as follows:
•
ASCII 422, ASCII 485 or ASCII 232 mode, according to the interface used.
•
Software handshake.
•
Baud rate 1200, 2400 or 9600, according to the driver EPROM version used.
•
8 bits, no parity.
The Powermeters communication addresses can be selected from 1 up to the maximum
number that the applied version of the driver supports.
Refer to the Powermeter User's Guide for information on how to set communications
parameters in your instrument.
2.5 Cable Connections
For the cable drawings, refer to Appendix C.
For RS-422/RS-485 balanced data transmission, a twisted pair cable should be used for each
communication link. To minimize reflections and reduce cross talk, it is recommended to
terminate the ends of lines with the termination resistor of 120
Ω
, as shown in Appendic es
C.2.1 and C.3.1.
When lines are routed through an electrically noisy environment, input protection against
switching or lightning induced surge voltages is required in addition to line termination. Surge
voltages can be generated by switching operations in power substations, or can occur as a
result of voltage deep fade, phase gating controls, contactor relay controls, etc. Transient
surge voltage effects may put the BASIC module or CPU out of action and in the worst case
lead to destruction of unprotected electronic components. The diagrams of the input protective
circuits are shown in Appendixes C.2.2 and C.3.2. You can also use complete surge voltage
protection units for RS-422/RS-485 communication available from Phoenix or from other
manufacturers of similar protective equipment.