Table 2-8 Communications Connections; Table 2-9 Communications Wiring Procedure - Honeywell VPR100 User Manual

Communications
The communications network is based on Honeywell protocols with a Master/Slave relationship. These are
the two protocols available; Binary and Modbus RTU. This network is configured around the IEEE
RS-422/485 multi-drop standard. The Master is a PC host running any software compatible with these
Honeywell protocols. A slave can be any instrument equipped with serial communications capability.
Refer to the product communications manual for additional details on the protocol. Binary: 51-52-25-54
and Modbus RTU: 51-52-25-66.
All communication equipment supporting the 422/485 (differential drive) must be correctly installed and
properly terminated to ensure a reliable network.
Table 2-8 shows the five connections per device.
Connection
TX+
TX-
COM
RX+
RX-
We recommend using a conduit for each cable, or at least separating them from high voltage lines or
magnetic fields.
Table 2-9 shows the communications wiring procedure. See Figure 2-12.
Step
1 Connect the Master's TX signals to each of the RX signals of the Slaves, and all the Slave's TX
signals to the Master's RX terminals, plus-to-plus and minus-to-minus.
2 Connect instrument to instrument in a serial or daisy chain fashion with the Master instrument at one
end and the last instrument at the other as shown in Figure 2-12.
3 Set only the last instrument's termination ON. All other slave instruments must be unterminated. To
change a termination setting, see "Setting The Communications Link Termination Jumper" in Section
9.4 for instructions.
ATTENTION
For CE compliance, a triple shielded cable (a shield around each of the twisted pairs, (which are tied together
and connected to the com. Terminal, TB2 Pin 3) plus an overall shield (the insulated outer shield is connected
to TB2 Pin 6, which is then connected to TB1 Pin 1 (earth ground)). The recommended cable of this type is
Belden 8728, 80C. DO NOT connect the outer shield to the internal shield ground. This will not provide
adequate immunity protection.
Required for CE application, but recommended for general use.
12/00

Table 2-8 Communications Connections

The positive signal of the transmitter
The negative signal of the transmitter
The shield of the communications cable
The positive signal of the receiver
The negative signal of the receiver

Table 2-9 Communications Wiring Procedure

VPR & VRX – User Manual
Meaning
Action
Installation
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