Rockwell Automation 2755 Enhanced Decoder Series B - Manual (Page 325)

Connecting to a Host E–7
Publication 2755-833
Figure E.5 Connecting NEMA Type 1 Decoder to DH485
Network
.
9
7
14
15
12
13
Shield
TxB +
TxA –
RS-485
Termination➁
Shield
Host Port
25-pin DB Connector
on Decoder
Host RS-485 Port
*
*
*
*
* Pin designations depend
on host device.
Shield ➀
➀ Only one of the devices in the network must have the cable shield connected to chassis ground.
Do this by connecting shield to pin 1 instead of pin 9.
➁ Enable line termination for the device at each end of the network. To enable line termination,
connect pins 12 and 13 together. For all other devices in the network, leave these pins open.
SIG GND SIG GND
TxB +
TxA –
The following parameters are fixed for DH485 communications:
•
8 Data bits
•
Even parity
•
1 Stop Bit
The host protocol options are:
•
DH485 PCCC-1. PCCC commands with write replies
•
DH485 PCCC-2. PCCC commands without write replies
•
DH485 ASCII-1. ASCII commands with responses
•
DH485 ASCII-2. ASCII commands without responses.
The communication interface and host protocol is selected during
configuration. See the Host Communications configuration screen.
Figure E.6 shows how to connect the NEMA Type 4 decoder to a
DH485 network. Use Belden cable 9842 (or equivalent).