Despatch Protocol Manager with Protocol Plus - Manual (Page 49)

Protocol Manager Software E-100
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network ports; “Communication In” and “Communication Out”. For shorter networking
runs, standard serial communication rated cables are available in a variety of lengths.
For example; Despatch P/N 161970 is a 25 foot serial cable. DB9 termination plugs are
also available from Despatch including P/N 161969; the required termination for a RS-
422 4-wire network. See remaining information if longer network cable lengths are
required.
Typically, RS-422A/RS-485A cables consist of three individually shielded twisted pairs;
one pair transmits data from the Host PC to the ovens, one pair transmits data from the
ovens to the host PC, and one conductor from the third pair is the signal common. The
remaining conductor of the third pair is unused. Cable such as Belden type 9843 should
be used.
The network requires a cable breakout junction box near each oven. 120 ohm
terminating resistors must be installed at each end of the RS-422/RS-485 network.
Refer to the following page for a simplified network wiring diagram. In this case, "To
Host PC" actually indicates a cable connection to the B&B adapter. The "PC Rcv" and
"PC Xmit" terminals refer to the B&B adapter's RD and TD terminals respectively.
Install the 120 ohm resistor between the RD+ and RD- terminals. Connect the GND
wire to the 422/485 GND terminal. The remaining termination resistor is applied at the
RD+ and RD-
terminals of the “last in line” networked oven.
RS-422/RS-485 allows communication over wires up to 1000 meters in length. It is
important to note that the associated runs from the oven’s Protocol Plus controller to
the breakout junction box be limited to 5 meters maximum. The junction boxes provide
a drop from the network cable to each oven. The cables marked “to Oven Controller”
are terminated with 9-
pin male subminiature “D” plug for mating with the oven
controller’s Communication In” serial data receptacle.
Wire drop the cable according to the following table:
Oven signal Junction box terminal 9-pin plug pin number
Rcv+ 5 2
Rcv- 4 7
Xmit+ 1 3
Xmit- 2 4
GND 3 5
The daisy chain drop cables may use shielded pairs. Cable shields should be
connected as follows:
At each junction box - to the box interior chassis.
At each drop cable 9-in plug-to the lug shell if conductive.
If a non-conductive shell is used, no connection is required.