Alcorn Mcbride V+ series, User Manual

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8-4 V16+ Hardware Reference
Ports 1-4: RS-232 or RS-485
Ports 1-4 are factory configured as RS-232C, but can be reconfigured as a group
as RS-485. The V16+ includes internal 220 Ohm termination for RS-485, so an
external terminator for the unit is not necessary. To configure ports 1-4 for RS-
485/422 operation, the 1488 and 1499 RS-232 Driver and Receiver chips must
be removed and 75174 and 75175 Driver and Receiver chips installed. (See the
Appendices for manufacturer’s part numbers.)
Pin RS-232 Connection RS-485 Connection
2 RS-232 RXD RS-485 RX+
3 RS-232 TXD RS-485 TX+
4 +12V Pull up +12V Pull up
5 GND GND
6 N/C RS-485 RX-
7 +12V Pull up +12V Pull up
9 N/C RS-485 TX-
Table 3 – Ports 1-4 connections for RS-232 and RS-485 operation.

Configuring Ports 1-4 as RS-485
1. Remove the 1489 chip from U49 and the 1488 chip from U54.
2. Install a 75174 chip in U46 and a 75175 RS-485 chip in U47.
3. Install a 10K R-Pack in RP12 and a 220 Ohm SIP in RP13.

Configuring Ports 1-4 as RS-232
1. Remove the 75174 chip from U46 and the 75175 chip from U47.
2. Install a 1489 chip in U49 and a 1488 chip in U54.
3. Remove the resistor packs located in RP12 and RP13.
Ports 5-15: RS-232
Ports 5-15 are permanently configured as RS-232C serial ports.
Pin Connection
2 RS-232 RXD
3 RS-232 TXD
4 +12V Pull Up
5 GND
7 +12V Pull Up
Table 4 – Ports 1-15 connections for RS-232 operation.