SMC Networks HECR Series Communications Manual page 7

Preparation for Communication
1 Preparation for Communication
Make preparation for using communication facility as follows.
1) Turn off the power switch of Thermo-con.
2) Connect communication cable to communication connector (RS-485 or RS-232C) of Thermo-con.
･Use twist pair shield cable as communication cable.
･Connect the host and thermo-con with the straight cable for RS-485 and the cross cable for RS-232C .
･Connect shielded cable of communication cable to communication connector and drop it to
FG(flame ground).
･Connection drawing for communication is shown in the Figures 1-1 and 1-2.
･Length of communication cable for RS-485 shall be limited to around 500[m] in total, and that for
RS-232C shall be 15[m].
･If communication cable for RS-485 is longer, set the terminating resistance (120 ohm) on.
3) Turn on the power switch of Thermo-con.
4) Select communication types for all Thermo-cons. See the operation manual of the details.
5) That's all for preparation of communication. Then if a communication command from the host
computer is given, each Thermo-con will reply it.
1-1
Host Computer
RS-485
Symbol
FG
+
-
SG
Figure1-1 Communication Connection (RS-485)
Host Computer
RS-232C
Symbol
FG
RD
SD
SG
RS
Short
CS
Figure1-2 Communication Connection (RS-232C)
Thermo-con
RS-485
Pin No Symbol
Connector
FG
shell
1 +
9 -
5 FG
Thermo-con
RS-232C
Pin No Symbol
Connector
FG
shell
2 RD
3 SD
5 SG
HECR