Chapter 11 Communication Specifications
11-4
(2) 1:n station communication on RS-485
When station number mode is used on RS-485, termination command (NAK FF) from host/PC can conflict with reply
from CPU, and CPU can fail to receive this command. Pay attention to this possibility at using this command.
(3) Port 2 hardware
The circuit diagram of port 2 and the signal list are shown in Figure 11.4 and Table 11.6 respectively.
Figure 11.4 Circuit diagram and pin numbers for port 2
Table 11.6 List of port 2 signals
Pin No. Signal Direction Meaning
abbreviation CPU Host
1] NC Not used
2] NC Not used
3] NC Not used
4] NC Not used
5] Vcc 5 V DC is supplied.
6] RSN Transmission request signal. When it is high low, CPU is ready to receive data..
7] SG Signal ground
8] CSP Receive enabled signal. When it is high, connected device is ready to receive data.
9] RT Terminating resistor (120Ω). Connect to pin 10 if necessary.
10] RDN Data received by the CPU -
11] RDP Data received by the CPU +
12] SDN Data sent by the CPU -
13] SDP Data sent by the CPU +
14] RSP Transmission request signal. When it is high level, CPU is ready to receive data.
15] CSN Receive enabled signal. When it is low, connected device is ready to receive data.

11.4 General purpose port (Port 1,2)

General purpose port can be configured either port 1 or port 2 by FUN 5 command in user program. General purpose port
enables serial communication to devices like bar code reader by TRNS/RECV command in user program.
Even if configured, the port works as general purpose port only CPU is in RUN status. Port is changed back to dedicated
port when CPU is in STOP status.
* General purpose port is supported by software version 1.30 (WRF051=H0130) or newer.
TX2
RX2
CS2
RS2
VCC
7] SG
5] VCC
14] RSP
6] RSN
15] CSN
8] CSP
13] SDP
12] SDN
10] RDN
11] RDP
9] RT

Micro processor

9]
10]
11]
12]
13]
14]
15]
1]
2]
3]
4]
5]
6]
7]
8]
General purpose port Dedicated port
CPU in STOP
General purpose port
CPU in RUN
Switching
automatically