C200H-LK201-V1 Host Link Module: Programming Legacy Omron C200H PLCs

The Omron C200H is a mid-1980s modular PLC platform that Omron formally discontinued, yet thousands of machines in the field still run on it. Program upload, edit, and monitor operations require either a CPU-mount host link module (3G2A6-LK201-EV1) or a single-slot backplane module (C200H-LK201-V1), both of which expose an RS-232C serial port to a host PC running SYSWIN or CX-Programmer. This reference consolidates the part numbers, port pinouts, cable requirements, peripheral-port hazards, and replacement strategy every maintenance engineer needs before touching a C200H that has no backup.

1. C200H Family Overview and Lifecyle Status

The C200H family spans several generations. Engineers must identify which CPU is in the chassis before selecting a host link, because the mount style and electrical interface differ between the original C200H and the later Alpha series (C200HS, C200HE, C200HG, C200HX).

The Alpha generation (C200HS and above) introduced an upgraded peripheral port with 5 V CMOS-compatible logic. The original C200H peripheral port uses different voltage levels and pinout, which is why cables designed for the Alpha line will physically seat but will either fail to communicate or, in the worst case, blow the CPU board fuse. This distinction is the single most common cause of field damage when an engineer grabs the nearest Omron programming cable off the shelf.

2. C200H-LK201-V1 Backplane Host Link Module

The C200H-LK201-V1 is a single-slot Host Link module that mounts in any open slot on the C200H / C200HS / C200H Alpha backplane and provides a standard RS-232C (also called RS-232-C) interface to a host computer. It is the preferred path when a free slot exists because it does not require any modification to the CPU and is electrically isolated from the peripheral-port hazard discussed above.

2.1 Part Status and Sourcing

Omron has marked the C200H-LK201-V1 as a discontinued part. Major authorized distributors still list the part in their catalogs for reference but flag the lifecycle as Obsolete and report zero factory stock:

• DigiKey - C200H-LK201-V1 listing: Lifecycle = Obsolete, Part Number Alias C200HLK201V1.
• Mouser - C200H-LK201-V1 listing: Description "HOSTLINK RS232-C", Lifecycle = Obsolete.

Although the part is obsolete at the factory, NOS (new-old-stock) and refurbished inventory routinely surfaces at Omron-specialist resellers. Verify warranty terms (typically 90 days to one year for refurbished) and request a burn-in test report before installing in a production line.

2.2 Module Specifications

3. 3G2A6-LK201-EV1 CPU-Mount Host Link

If every backplane slot is populated, the original C200H (only) supports a CPU-mount host link that snaps onto the long 48-pin horizontal connector on the front of the CPU. This is part number 3G2A6-LK201-EV1 and it brings the same RS-232C Host Link capability as the C200H-LK201-V1 without consuming a slot.

The CPU-mount host link is mechanically compatible with the C200H only. C200HS and C200H-Alpha CPUs expose a different 48-pin connector geometry, so the 3G2A6-LK201-EV1 will not seat correctly and must not be forced. For the C200HS and Alpha, use the backplane C200H-LK201-V1 instead.

4. Port Extenders: C200H-BP001 and C200H-BP002

Both the C200H-LK201-V1 (in some chassis configurations) and the 3G2A6-LK201-EV1 may require a port extender to clear adjacent modules and present the 25-pin connector at the chassis lip:

• C200H-BP001 - short extender, typical for CPU-mount host link applications.
• C200H-BP002 - extended-length variant for deep rack or wiring-duct clearance.

The port extender does not appear in current Omron price lists. Treat it as a long-lead part and source it together with the host link module. If the extender is unavailable, a third-party DB-25 male-to-female hood extension cable is an acceptable substitute provided the shield is bonded at one end only.

5. RS-232C Cable Requirements

The LK201 family presents a DB-25 female on the PLC side. The host PC almost always terminates in DB-9 (legacy industrial PCs and many modern industrial tablets still have DB-9; USB-to-RS-232 adapters are also acceptable when based on FTDI FT232 or equivalent industrial-grade bridges).

For Host Link protocol on the C200H, the standard cable is a straight-through RS-232C shielded cable wired as follows. Note that the C200H-LK201-V1 uses a minimal subset of the RS-232C signals; RTS/CTS handshaking is not required at the default Host Link settings.

5.1 Standard Host Link Communication Parameters

6. Peripheral Port: What It Is, What It Is Not

The C200H CPU faceplate has a second connector under a small drop-down flap. This is the Peripheral Port, a 16-pin connector intended only for the C200H-PRO27 handheld programmer. Connection is via Omron cable C200H-CN222. The C200H-PRO15 "handheld" programmer is a different device: it occupies the 48-pin horizontal connector shared with the host link modules and the port extenders, not the Peripheral Port.

The Peripheral Port is the single most abused connector on the C200H. The following cables physically fit the Peripheral Port socket and will either fail silently or destroy the CPU:

The Alpha series (C200HS and above) upgraded the Peripheral Port to a 5 V CMOS logic level that is compatible with the CQM1-CIF02 / CPM1-CIF01 adapters. This change is what made the adapters viable on Alpha hardware. The original C200H does not have that protection, so the level translators in the newer adapters do not engage and the raw RS-232 line driver hits the 5 V CMOS input on the C200H, which is what blows the fuse.

7. Software: SYSWIN and CX-Programmer

SYSWIN version 3.x is the canonical programming environment for the C200H family and supports every C200H, C200HS, and C200H-Alpha CPU directly. It uses the standard Omron Host Link protocol and communicates at the parameters listed in section 5.1.

CX-Programmer (versions up to 9.x) also supports the C200H family under the "C200H" device family selection. For modern Windows hosts (Windows 10 / 11), use CX-Programmer 9.6 or later, install in XP compatibility mode if necessary, and create a logical COM port mapped to the USB-to-RS-232 adapter. The default baud/parity/data/stop settings in CX-Programmer's C200H device driver match the values in the table above.

SYSWIN can be run inside a Windows XP Mode virtual machine under Windows 7 Professional, or under DOSBox / PCem for legacy host compatibility. When using a USB-to-RS-232 adapter, select an FTDI-based unit and explicitly assign a fixed COM port number (e.g., COM3) from Device Manager to keep SYSWIN's port list predictable.

8. Program Upload Procedure

The following procedure applies to a C200H-LK201-V1 in an open backplane slot and a host PC running SYSWIN 3.x.

8.1 Prerequisites

1. C200H-LK201-V1 module installed and seated in an open backplane slot.
2. PLC powered and in PROGRAM mode (key switch on CPU set to PROGRAM).
3. RS-232C shielded cable, DB-25 male to DB-9 female, wired per section 5.
4. SYSWIN 3.x installed on the host PC, with the correct COM port selected.
5. Host Link parameters on the LK201 DIP switches: Node 00, 9600, 7-E-2.

8.2 Step-by-Step

1. Power the PLC. Observe the LK201 PWR LED is steady green.
2. Verify the LK201 RD and SD LEDs flash once at power-up, indicating the module passed self-test.
3. Connect the RS-232C cable from the LK201 faceplate to the host PC COM port.
4. Launch SYSWIN. From the PLC menu select Online, then Connect.
5. In the connection dialog, set:
   • Network: Host Link
   • COM Port: 3 (or as assigned)
   • Baud: 9600
   • Data: 7, Parity: Even, Stop: 2
   • Node: 00
6. Click Test. A successful test returns "Host Link OK".
7. From the File menu select Save Program from PLC to File. Specify a filename with the .csy or .cxt extension depending on the SYSWIN / CX-Programmer version.
8. After the upload completes, verify the program checksum by comparing the displayed file size and ladder area count against a known-good program from the same model, or by downloading to a second C200H and confirming identical I/O behavior.

9. Sourcing Strategy for Obsolete Parts

For factory-original, never-installed parts, expect lead times in the 8-16 week range or unavailability. The practical strategy is:

1. Pull two C200H-LK201-V1 modules from non-critical surplus equipment for every production line that must be supported. Burn-in test each for at least 48 hours at 35 degC ambient.
2. Stock at least one C200H-PRO27 handheld programmer and one C200H-CN222 cable per site. The handheld programmer is the fastest offline backup tool and does not require a free backplane slot.
3. Maintain a verified host PC image with SYSWIN and CX-Programmer installed, locked to a specific COM port numbering scheme. USB-to-RS-232 adapters should be the same SKU across the site to avoid driver churn.
4. For long-term support, plan a migration to a current-generation Omron platform (CP1E, CP1H, NJ, or NX) using a documented I/O and program conversion. The Omron CX-Programmer migration tool can import C200H ladder and remap I/O addresses.

10. Field-Proven Safety Checklist

Before applying power with a host link module installed for the first time on a machine that has been running unattended, complete the following:

• Confirm the CPU is in PROGRAM mode and that the process is in a safe state. Uploading does not write to the PLC, but a misclick in the software can transition the PLC to MONITOR or RUN.
• Verify the LK201 faceplate DIP switches match the planned node address and baud rate. The factory default is node 00, 9600 bps.
• Confirm the RS-232C cable shield is bonded at the PLC end only. Floating or double-bonded shields inject common-mode noise into the Host Link UART and produce intermittent timeouts.
• Measure +5 V and +24 V on the CPU power supply before insertion. A sagging +5 V rail (below 4.85 V) can cause the LK201 to repeatedly reset its Host Link state machine.
• Mark the Peripheral Port with a label stating "PRO27 ONLY - DO NOT INSERT CQM1/CPM1 ADAPTER". This is the single most effective preventive measure against field damage.

11. Troubleshooting Matrix

12. Specifications Summary

FAQ