12286 Rev 2
Page 3 of 6
6.3 Specifications
Serial Communication Specifications
Specifications
Serial RS-422
Four wire; two differential pair. Jumper JP6 is removed and
jumper JP10 is installed on circuit board.
Serial RS 485
Two wire; single differential pair. Jumper JP6 is installed and
jumper JP10 is removed from circuit board.
Type:
Dedicated Network
Length of Network:
Maximum length not to exceed 4000 feet (1200 meters). RS485
Specification guidelines provide length as a function of allowable
distortion; minimum acceptable output voltage; terminating
resistance; baud rate and selected cable loop resistance.
Nodes:
Up to 64 uniquely addressable SENTRY TIM-100/120s on a
given network. Note: Specification guidelines for RS485 provide
for a maximum of 32 units, including the host, on a single
network. A repeater is required to add an additional 32 units for
a maximum total of 64 SENTRY TIM-100/120s.
Communication Rate:
9600 Baud
Data:
8 data bits
Characters:
All messages between Host and SENTRY TIM-100/120s are
made up of ASCII characters.
Parity:
No parity
Start bit:
1 start bit
Stop bit:
1 stop bit
Protocol:
Two-pass with a two character checksum for message
transactions. Host initiates transaction by sending a command to
one of the SENTRY TIM-100/120 units on the network. The
addressed Unit verifies that the command is valid and then
executes the command. Upon command completion, the
SENTRY TIM-100/120 unit returns an acknowledgment along
with any requested data. Command messages and messages
containing returned data from a TIM-100/120 unit includes a
message checksum to insure secure communications.
Interface Connector:
RJ-12, 6 pin female connector on the SENTRY TIM-100/120.
RS422 two differential pairs, multi-drop capability.
