Communication modules enable the connection with an external communication partner to exchange data. Comprehensive parameterization options make it possible to adapt the control flexibly to the communication partner.
Modbus RTU master creates a Modbus RTU network for up to 30 Modbus slaves.

The following communication modules are available:

CM PtP RS232 BA;
communication module with RS232 interface for the protocols Freeport, 3964(R) and USS; 9-pin sub D connector, max. 19.2 Kbit/s, 1 KB frame length, 2 KB receive buffer
CM PtP RS232 HF;
communication module with RS232 interface for the protocols Freeport, 3964(R), USS and Modbus RTU; 9-pin sub D connector, max. 115.2 Kbit/s, 4 KB frame length, 8 KB receive buffer
CM PtP RS422/485 BA;
communication module with RS422 and RS485 interface for the protocols Freeport, 3964(R) and USS; 15-pin sub D socket, max. 19.2 Kbit/s, 1 KB frame length, 2 KB receive buffer
CM PtP RS422/485 HF;
communication module with RS422 and RS485 interface for the protocols Freeport, 3964(R), USS and Modbus RTU; 15-pin sub D socket, max. 115.2 Kbit/s, 4 KB frame length, 8 KB receive buffer

Siemens Communication Modules S7-1500 Product Specifications:

Article number	6ES7540-1AD00-0AA0	6ES7541-1AD00-0AB0	6ES7540-1AB00-0AA0
	S7-1500, CM PTP RS232 BA	S7-1500, CM PTP RS232 HF	S7-1500, CM PTP RS422/485 BA
General information
Product type designation	CM PtP RS 232 BA	CM PtP RS 232 HF	CM PtP RS 422 / 485 BA
Product function
● I&M data	Yes; I&M 0	Yes; I&M 0	Yes; I&M 0
● Fast startup	Yes	Yes	Yes
Engineering with
● STEP 7 TIA Portal configurable/integrated from version	V12 / V12	V12 / V12	V12 / V12
● STEP 7 configurable/integrated from version	V5.5 SP2 with GSD file	V5.5 SP2 with GSD file	V5.5 SP2 with GSD file
● PROFIBUS from GSD version/GSD revision	– / –	– / –	– / –
● PROFINET from GSD version/GSD revision	V2.3	V2.3 / –	V2.3
Installation type/mounting
Rail mounting	Yes; S7-1500 mounting rail	Yes; S7-1500 mounting rail	Yes; S7-1500 mounting rail
Supply voltage
Design of the power supply	system power supply	system power supply	system power supply
Input current
Current consumption (rated value)	50 mA; From the backplane bus	50 mA; From the backplane bus	43 mA; From the backplane bus
Power
Power available from the backplane bus	0.75 W	0.75 W	0.65 W
Power loss
Power loss, typ.	0.6 W	0.6 W	0.6 W
Address area
Address space per module
● Inputs	8 byte	8 byte	8 byte
Interface types
RS 232
● Transmission rate, max.	19.2 kbit/s	115.2 kbit/s
● Cable length, max.	15 m	15 m
● RS 232 auxiliary signals	RTS, CTS, DTR, DSR, RI, DCD	RTS, CTS, DTR, DSR, RI, DCD
RS 485
● Transmission rate, max.			19.2 kbit/s
● Cable length, max.			1 200 m
RS 422
● Transmission rate, max.			19.2 kbit/s
● Cable length, max.			1 200 m
● 4-wire full duplex connection			Yes
● 4-wire multipoint connection			No
Protocols
Integrated protocols
Freeport
— Telegram length, max.	1 kbyte	4 kbyte	1 kbyte
— Bits per character	7 or 8	7 or 8	7 or 8
— Number of stop bits	1 or 2 bit	1 or 2 bit	1 or 2 bit
— Parity	None, even, odd, always 1, always 0, any	None, even, odd, always 1, always 0, any	None, even, odd, always 1, always 0, any
3964 (R)
— Telegram length, max.	1 kbyte	4 kbyte	1 kbyte
— Bits per character	7 or 8	7 or 8	7 or 8
— Number of stop bits	1 or 2 bit	1 or 2 bit	1 or 2 bit
— Parity	None, even, odd, always 1, always 0, any	None, even, odd, always 1, always 0, any	None, even, odd, always 1, always 0, any
Modbus RTU master
— Address area		1 to 247, extended 1 to 65535
— Number of slaves, max.		1
MODBUS RTU slave
— Address area		1 to 247, extended 1 to 65535
Telegram buffer
● Buffer memory for telegrams	2 kbyte	8 kbyte	2 kbyte
● Number of telegrams which can be buffered	255	255	255
Interrupts/diagnostics/status information
Diagnostics function	Yes	Yes	Yes
Alarms
● Diagnostic alarm	Yes	Yes	Yes
● Hardware interrupt	No	No	No
Diagnoses
● Wire-break	Yes	Yes	Yes
Diagnostics indication LED
● RUN LED	Yes; green LED	Yes; green LED	Yes; green LED
● ERROR LED	Yes; red LED	Yes; red LED	Yes; red LED
● Receive RxD	Yes; Yellow LED	Yes; Yellow LED	Yes; Yellow LED
● Transmit TxD	Yes; Yellow LED	Yes; Yellow LED	Yes; Yellow LED
Potential separation
between backplane bus and interface	Yes	Yes	Yes
Isolation
Isolation tested with	707 V DC (type test)	707 V DC (type test)	707 V DC (type test)
Ambient conditions
Ambient temperature during operation
● horizontal installation, min.	0 °C	0 °C	0 °C
● horizontal installation, max.	60 °C	60 °C	60 °C
● vertical installation, min.	0 °C	0 °C	0 °C
● vertical installation, max.	40 °C	40 °C	40 °C
Altitude during operation relating to sea level
● Installation altitude above sea level, max.	5 000 m; restrictions for installation altitudes > 2 000 m, see ET 200MP system manual	5 000 m; restrictions for installation altitudes > 2 000 m, see ET 200MP system manual	5 000 m; restrictions for installation altitudes > 2 000 m, see ET 200MP system manual
Decentralized operation
to SIMATIC S7-300	Yes	Yes	Yes
to SIMATIC S7-400	Yes	Yes	Yes
to SIMATIC S7-1500	Yes	Yes	Yes
to standard PROFINET controller	Yes	Yes	Yes
Dimensions
Width	35 mm	35 mm	35 mm
Height	147 mm	147 mm	147 mm
Depth	127 mm	127 mm	127 mm
Weights
Weight, approx.	0.22 kg	0.22 kg	0.22 kg