Omron C200H PLC RS-232 and Peripheral Port Communication Setup

Overview

The Omron C200H, C200H-α (C200H alpha), C200HG, and C200HX CPU families expose two distinct serial channels for engineering access: a built-in RS-232C port and a high-density peripheral port. Both are usable for ladder upload/download, online editing, and HMIs (such as the NT-series and NS-series), but they require different cables, different protocol modes, and different DIP switch or DM-area settings. The two channels are not redundant—they coexist, and selecting the wrong protocol on one of them is the most common cause of "computer cannot talk to PLC" failures in the field.

This procedure covers three decisions an engineer must make before plugging in a PC:

1. Which physical port (built-in RS-232C or peripheral) will be used?
2. Which protocol (Host Link / C-mode, NT-Link 1:1, or NT-Link 1:N) is loaded on that port?
3. Which DIP switch and DM area words correspond to that protocol?

After these are fixed the wiring collapses to either a straight DB9 null-modem cable (RS-232C Host Link) or a CPM1-CIF01 adapter plugged into the peripheral port. The HMI is not required for any of these decisions—any NT31/NS5/NS8 can be unplugged while the PC is online.

Prerequisites

• Omron C200H / C200H-α / C200HG / C200HX CPU module (CPU01, CPU03, CPU11, CPU21, CPU23, CPU31, CPU33, or later).
• Programming software: CX-Programmer v9.x or later, or legacy Syswin 3.x for older workstations (Omron Industrial Automation support portal).
• Cable option A — built-in RS-232C: Omron XW2Z-200S-CV (2 m) or XW2Z-500S-CV (5 m) null-modem DB9 male/female assembly.
• Cable option B — peripheral port: CPM1-CIF01 (RS-232C adapter, mini-DIN to DB9 female) or CPM1-CIF11 (RS-422/485 adapter) per CPM1-CIF01 product page.
• Flat-blade screwdriver for CPU faceplate DIP access.
• Reference manuals: C200H Operation Manual (W197), C200H-α Operation Manual (W353), NT-series Host Link manual (V028).

Communication Protocol Selection

The C200H CPU runs only one protocol on each port at a time, and each protocol carries strict baud-rate and frame-format constraints. Select the protocol that matches the equipment at the other end of the cable.

Rule of thumb: If the PC is the only device on the cable, leave the port in Host Link. If a real HMI is on the bus, switch that HMI's port to NT-Link and leave the PC's port as Host Link on the other channel. Mixing Host Link and NT-Link on the same cable produces framing errors and intermittent disconnects.

C200H DIP Switch Configuration

The C200H CPU faceplate carries two 4-position DIP switches labelled SW1 and SW2 (positions 1 through 4 on each). Switch state is read at power-up and on each transition to RUN/MONITOR; runtime changes are ignored.

For first-time bring-up:

1. Set SW1 pin 4 = OFF if you intend to configure the RS-232C port through DM6645–DM6649; set it to ON if you want the factory default (Host Link, 9600 bps, 7E2, unit 00).
2. Set SW2 pin 1 = OFF for peripheral-port DM configuration, or ON to revert to standard Host Link on the peripheral port.
3. Keep SW1 pin 1 OFF unless you want to lock the program memory.
4. Keep SW1 pin 2 OFF unless the machine must boot into RUN unattended.

DM Area Configuration for Host Link

When SW1 pin 4 is OFF, the RS-232C port reads its parameters from DM6645–DM6649 at every CPU cycle reset. Common settings:

Mirror the same layout on DM6650–DM6654 for the peripheral port (read when SW2 pin 1 is OFF). The peripheral port supports Host Link and NT-Link but never runs at the higher 38400/115200 bps of NT-Link 1:N.

RS-232C Port — Host Link Cable and Pinout

The built-in RS-232C port on the C200H is a female DB-9. The PC end is a male DB-9. The two are joined by a null-modem cable that swaps TD/RD and loops RTS/CTS and DTR/DSR.

If a pre-built Omron cable is not available, the minimum workable null modem for Host Link requires only three conductors plus the handshaking loopbacks on the PC end:

PC DB9 male                C200H DB9 male (use gender changer)
1  DCD  ---------- NC ---------- 1  NC
2  RXD  ---------- ----------> 3  RD
3  TXD  <---------- ---------- 2  SD
4  DTR  ---+                 4  RS
6  DSR  ---+-- loopback      5  CS
7  RTS  ---+                 9  SG
8  CTS  ---+-- loopback
5  GND  ---------- ----------

Recommended cable: Omron XW2Z-200S-CV (2 m) or XW2Z-500S-CV (5 m). These are shielded, pre-built null modems with both ends DB9 and are the supported cable for Host Link upload/download. Reference: Omron Industrial Automation portal.

Peripheral Port — CPM1-CIF01 Adapter

The peripheral port on C200H uses a 5-pin mini-DIN connector (similar to PS/2 mechanically but proprietary electrically). It is not an RS-232C port and will not accept a DB9 directly. The CPM1-CIF01 plugs into this port and breaks out a DB9 female RS-232C, which then takes the same null-modem cable described above.

If you do not have a CPM1-CIF01 and do not wish to fabricate one, you can buy a pre-made assembly (Omron CS1W-CN118 or third-party equivalent) that ends in DB9 female. If you must hand-wire it, the peripheral-port pinout is:

C200H peripheral port (mini-DIN, looking at PLC face)

      3   4
   2         5
      1

Pin 1 = +5 V (do not tie to PC side)
Pin 2 = SD (PLC sends)
Pin 3 = RD (PLC receives)
Pin 4 = NC
Pin 5 = SG
Shield = chassis

Map pin 2 to PC RXD (PC pin 2), pin 3 to PC TXD (PC pin 3), and pin 5 to PC GND (PC pin 5). Tie +5 V (pin 1) only if the adapter requires bus power; for a passive breakout, leave it disconnected.

CX-Programmer / Syswin Settings

On the PC side, both CX-Programmer and Syswin need the matching network parameters before they will handshake.

CX-Programmer (v9.x and later)

1. Open the project. PLC → Auto Online → Direct Online.
2. Select Serial Port as the connection type.
3. Set COM port to the physical port (COM1 typical).
4. Set baud to match DM6646 / DM6651.
5. Frame format forced to 7,E,2 for Host Link.
6. Network address = 0; Node address = 0 (Host Link unit number from DM6647).
7. Click Connect. The CPU should reply with a banner containing the model code (e.g. CPU21-E).

Syswin (legacy)

1. Project → Communications.
2. Select the COM port.
3. Baud = 9600, Frame = 7E2, Unit = 00.
4. Online → Connect.

CX-Programmer Driver Settings — Reference

Configuring NT-Link 1:1 for an HMI

If the goal is to dedicate the built-in RS-232C port to an NT31 (or NS5/NS8) panel, switch the port to NT-Link 1:1:

1. Place the CPU in PROGRAM mode.
2. In CX-Programmer, edit DM6645 = 0002 (NT-Link 1:1).
3. Set DM6646 = 07 (19200 bps, recommended for HMI tag throughput).
4. Set DM6647 = 0000 (unit 0, no delay).
5. Power cycle the CPU. The HMI's own "Comm" menu must also be set to NT-Link 1:1 at 19200, 7E2.
6. On the HMI side the "PLC model" field must read C200H or C200Hα; selecting CQM1H or CP1E will produce no response because the FINS command sets differ.

Verification Procedure

1. Confirm the cable: continuity check on pins 2, 3, 5; no continuity between 2 and 3 (they must be crossed).
2. Confirm DIP state: SW1 pin 4 in the expected position; SW2 pin 1 in the expected position. Power off and on so the PLC re-reads the switches.
3. Confirm DM: dump DM6645–DM6654 from CX-Programmer and verify against the table above.
4. Open CX-Programmer, click Online → Connect. The status bar should report the CPU model within 3 seconds.
5. Upload the program: PLC → Transfer From PLC → Programs. If upload completes, link is healthy.
6. Cycle power and reconnect to confirm the session survives a warm restart.

Troubleshooting Matrix

Field-Proven Caveats

• The C200H CPU reads DIP switches at power-up only. Editing DM words at runtime and expecting immediate effect does not apply to SW1/SW2 positions—it applies only to the parameters they select.
• The peripheral port is half-duplex in NT-Link mode. Do not parallel it with a programming console on the same mini-DIN—use the CPM1-CIF01 exclusively.
• When DM6645 is set to 0004 (peripheral bus), only the Omron C200H-PR027 Programming Console responds. A PC running CX-Programmer will get "unrecognized command."
• Older CX-Programmer revisions (pre-v7) do not list C200Hα under the device drop-down. Manually select "C200H" and the CPU will still respond.
• Battery-backed DM retention depends on the C200H-BAT08 cell. With a dead battery, DM6645–DM6654 revert to zero (Host Link default), which is usually benign but breaks NT-Link configurations on every cold start.

FAQ