Omron CJ1W-SCU21-V1 — CJ Serial Unit, 2 x RS-232C
SKU: CJ1W-SCU21-V1USD 105.00
CJ-series serial communication unit with two RS-232C ports, 5 VDC backplane powered, 38.4 kbps, host link / NT link / Modbus-RTU slave.
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Product Overview
The Omron CJ1W-SCU21-V1 is the CJ-series CPU bus serial communication unit with two RS-232C ports. Each port connects to a single point-to-point RS-232C device at up to 15 m, and each port can run a different protocol independently. The unit pulls 0.28 A from the 5 VDC CJ backplane -- no separate power supply -- and slots into any CPU bus unit position on the CJ rack. Pick the SCU21-V1 when the cabinet needs two short-distance RS-232C devices on one CPU (for example, a barcode reader and a serial-label printer, or two inverters on Host Link).
SCU vs SCU@2 high-speed
The SCU2x-V1 is the standard-speed type at up to 38.4 kbps. The SCU@2 (SCU22 / SCU32 / SCU42) is the high-speed type that adds 115.2 kbps on RS-232C and 230.4 kbps on RS-422A / RS-485 plus the NT-AL001 RS-232C / RS-422A link adapter for 1:N communication. Pick the SCU@2 when a 38.4 kbps ceiling is too slow for the device. For a panel that needs both RS-232C and RS-422A / RS-485, pick the SCU41-V1 mixed-port sibling at 0.38 A. For a 2-port RS-422A / RS-485 install, pick the SCU31-V1.
Per-port protocols
Each of the two ports can be set independently to protocol macro (a sequence of predefined messages), Host Link (SYSWAY-compatible master / slave for CX-Programmer upload), NT Link 1:N (for an NS / NB HMI panel on the SCU port), serial gateway (auto FINS / Host Link / Modbus-RTU conversion), no-protocol (raw byte send / receive), or Modbus-RTU slave (the unit acts only as a slave, not as a master). The serial gateway mode is the typical pick when a third-party Modbus-RTU sensor needs to land on a CJ1 / NJ CPU as FINS.
Before ordering
Confirm the CJ rack has a free CPU bus unit slot (each SCU occupies one CPU-bus unit position). Up to 16 CPU-bus units sit on one CJ rack, so up to 16 SCUs and 32 serial ports per system. Each SCU draws 0.28 A from the 5 VDC backplane, so on a fully-loaded 16-SCU rack the backplane draw tops out around 5 A -- pick the CJ1W-PA205R (5.0 A at 5 VDC) or the CJ1W-PD025 (5.0 A at 5 VDC) PSU. For long-distance RS-422A 1:N, attach the NT-AL001 link adapter to a port and pick the SCU@2 high-speed type.
Key Features
- CJ-series CPU bus serial communication unit with TWO RS-232C ports on D-Sub 9-pin connectors
- Two independent RS-232C point-to-point links up to 15 m cable run
- Each port sets independently: protocol macro, host link, NT link (1:N), serial gateway, no-protocol, Modbus-RTU slave
- 5 VDC 0.28 A from the CJ backplane -- no separate power supply required
- Standard-speed communications at 1,200 to 38,400 bps (the SCU@2 high-speed type adds 115.2 / 230.4 kbps)
- RS-422A / RS-485 1:N multidrop via the NT-AL001 link adapter on each RS-232C port (the SCU21-V1 has no RS-422A port built in)
- Modbus-RTU acts as SLAVE only -- not as a master
- Up to 16 SCUs per CJ rack, up to 32 serial ports system-wide
- COMM1 / COMM2 + RUN / ERC front-panel LEDs
- Mounts in any CJ CPU-bus unit slot (CJ1M / CJ1H / CJ2H / CJ2M CPU racks)
- Pair with the NT-AL001 RS-232C to RS-422A / RS-485 link adapter for 1:N multidrop
- Not hot-swappable -- mount or replace with the CJ rack powered off (same as other CJ CPU-bus units)
- Distinguishing feature vs SCU31-V1: SCU21-V1 is two RS-232C, SCU31-V1 is two RS-422A/485, SCU41-V1 is mixed
- SKU: CJ1W-SCU21-V1
- Series: CJ-series CPU Bus Serial Communication Unit
Best-Fit Applications
- Two short-distance RS-232C devices on one CJ CPU -- barcode reader + serial-label printer, or two inverters on Host Link
- Modbus-RTU slave gateway from a third-party inverter / temperature controller / power meter to a CJ1 / NJ CPU via the SCU serial-gateway mode
- Two Host Link master ports for connecting to older C-series or C200H PLCs on a migration retrofit
- Pair with a CJ1W-CIF11 RS-232C to RS-422A adapter on each port for 1:N long-distance wiring (the CIF11 converts the RS-232C port to RS-422A / RS-485)
- Pick the SCU@2 high-speed sibling (SCU22 / SCU32 / SCU42) when 38.4 kbps is too slow for the device or 230.4 kbps RS-422A / RS-485 is needed
Buying Checklist
- Pick CJ1W-SCU21-V1 for a CJ CPU-bus serial unit with two RS-232C ports at 0.28 A from the 5 VDC backplane.
- Pick CJ1W-SCU31-V1 instead for two RS-422A / RS-485 ports when long-distance multidrop is needed.
- Pick CJ1W-SCU41-V1 instead when one RS-232C and one RS-422A / RS-485 port are both needed on a mixed-port panel.
- Pick CJ1W-SCU22 (SCU@2 high-speed) instead when 38.4 kbps is too slow or 115.2 kbps RS-232C is needed.
- Pick NT-AL001 instead to convert an RS-232C port on the SCU21-V1 to RS-422A for 1:N multidrop wiring.
- Confirm the CJ rack has a free CPU-bus unit slot (up to 16 CPU-bus units per CJ1 / CJ2 CPU rack).
Technical Specifications
| Series | CJ-series CPU Bus Serial Communication Unit |
|---|---|
| Model | CJ1W-SCU21-V1 (two RS-232C ports) |
| Port 1 / Port 2 | RS-232C, D-Sub 9-pin connector |
| Modes | Full duplex RS-232C, point-to-point |
| Communication Speed | 1,200 / 2,400 / 4,800 / 9,600 / 19,200 / 38,400 bps |
| Cable Distance | RS-232C 15 m; RS-422A / RS-485 500 m via NT-AL001 adapter on each port |
| Power | 0.28 A from 5 VDC CJ backplane (no external supply) |
| Protocols per Port (CJ mode) | Protocol macro, host link, NT link 1:N, serial gateway, no-protocol, Modbus-RTU slave |
| Modbus Role | SLAVE only (the SCU does not act as a Modbus-RTU master) |
| Mounting | One CJ CPU-bus unit slot, DIN-rail |
| System Capacity | Up to 16 SCUs per CJ rack, up to 32 serial ports per system |
| Approvals | UL / cULus (Class 1 Div 2) / CE / NK / Lloyd; MADE IN JAPAN |
Resources & Downloads
FAQ for CJ1W-SCU21-V1
What is the difference between CJ1W-SCU21-V1 and CJ1W-SCU31-V1?
The SCU21-V1 has two RS-232C ports (D-Sub 9-pin) for short-distance point-to-point devices (barcode readers, label printers, legacy inverters at up to 15 m). The SCU31-V1 has two RS-422A / RS-485 ports (5-pin terminal block) for long-distance multidrop wiring up to 500 m. Both pull power from the 5 VDC CJ backplane (the SCU21-V1 draws 0.28 A, the SCU31-V1 draws 0.38 A) and run the same per-port protocol set. Pick the SCU21-V1 when both field devices are short-distance RS-232C; pick the SCU31-V1 for an RS-422A / RS-485 multidrop chain.
What protocols does each SCU port support?
On a CJ system, each port can independently run protocol macro (a sequence of predefined send / receive messages), host link (SYSWAY-compatible, for CX-Programmer upload or a third-party SYSWAY master), NT link 1:N (for an NS / NB HMI panel on the same rack), serial gateway (automatic FINS / Host Link / Modbus-RTU conversion), no-protocol (raw byte send / receive), or Modbus-RTU slave (the SCU only acts as a slave, not as a master). On an NJ system the per-port list drops to protocol macro, serial gateway, no-protocol, and Modbus-RTU slave -- host link and NT link are not supported on the NJ via the SCU.
Can the SCU21-V1 talk to a Modbus-RTU master?
Yes -- as a slave. The SCU21-V1 Modbus-RTU mode is slave only; it does not act as a Modbus-RTU master to third-party slaves on the network. For a Modbus-RTU master port on the CJ CPU, use the CJ1W-SCU41-V1 mixed-port sibling (with the SCU running the master mode on the RS-422A / RS-485 port) or the CJ1W-CIF12-V1 isolated RS-485 option board fitted to the CPU option board slot. The Modbus-RTU slave is the typical pick when a third-party sensor (inverter, power meter, scale) needs to land on the CPU as FINS via the serial-gateway mode.
Can the SCU21-V1 run at 115.2 or 230.4 kbps?
No. The SCU21-V1 is the standard-speed type with a top speed of 38.4 kbps on each port. For 115.2 kbps (RS-232C) or 230.4 kbps (RS-422A / RS-485) pick the SCU@2 high-speed type: the SCU22 (2 x RS-232C, 0.28 A), the SCU32 (2 x RS-422A / RS-485, 0.40 A), or the SCU42 (1 x RS-232C + 1 x RS-422A / RS-485, 0.36 A). The SCU@2 also supports the NT-AL001 RS-232C to RS-422A adapter for 1:N link (the SCU21-V1 with the NT-AL001 adapter is limited to 38.4 kbps on the chain). Confirm the field device actually needs more than 38.4 kbps before paying the SCU@2 premium -- most Modbus-RTU slaves happily run at 19.2 kbps.
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